To get Soda Popper equipped by Scout. You must first craft:

Bonk Atomic + The Force a Nature + Scrapped Metal.

If you play demoman on a map with capture points, don't forget to put stickies on it. If an enemy walks on it, you can explode him with your stickies. But don't be dead at that time because your bombs will be destroyed if you're killed.

You can also do high jumps with your stickies: jump on it and explode it. It will cost life but it can buy time for you or for reaching places that only a soldier or a demoman can (like the roof on Gravelpit, capture point B).

Don't forget that stickies are more efficient for destroying buildings than your normal grenades. It can be devastating if you're ubered.

If you are building/repairing a building, never stand still. This makes you vulnerable to Spies. Always hit anyone who comes near you and your buildings with the wrench.

The obvious way would be to jump into water but only a few official maps are having a pool, a river, a lake, or anything else with enough liquid to get rid of the flames.

The only classes that can heal and extinguish people at the same time are the Medic or the Engineer (thanks to his dispenser) but you don't have always one near you or even in the team.

So what do you if you're on fire or if you see someone on fire? Depending on your class and thanks to new weapons or updates to the game, you can help.

SNIPER
Use the Jarate on you or on your team to get rid of the flames. It seems that the Sidney Sleeper doesn't have this effect despite sharing the same yellow liquid.

PYRO
When carrying the Flamethrower or the Degreaser, you can use the airblast function (right click) to extinguish your teammates.

SCOUT
If you have the Mad Milk, use it in the same way as the Jarate: throw it on yourself or your teammates.

Go to Options, click the Keyboard tab and then Advanced to turn on Fast Weapon Switching. You can now scroll through the weapons without clicking to equip them.

As you know, spies can be disguised as a teammate and make a lot of damages in your defense by sapping sentries/teleporters/dispensers, killing you by behind (and a backstab is fatal, no matter how high your health is) and cap a point when the previous is just capped by his team and when or your team is dead or is still trying to prevent the teams to advance.

So, spotting a spy when he's disguised or cloaked is vital if you want to counter his plans. Here is a list of different ways to recognize an enemy spy, except the most obvious one for you when you're running into a spy with your name.

There are three common ways, the most frequent in the game, and a lot of secondary tips that can be useful, mostly for the poor engineers, the main target.

The first one is the spy checking. If anybody can spycheck with melee weapons for not using ammo or for the heavy to use his minigun while he's next to a dispenser, the most efficient way to do it is to burn a spy. The pyro is using a flamethrower and when he's spreading his fire, he can put on fire a teammate. As friendly fire isn't enabled on TF2, that can only mean that the one he puts on fire is a spy. Also, the fire can put fire to cloaked spies. So, the pyro is very useful when it comes to defend the team sentries. He can detect spies with his fires. If an engineer is asking spycheck, a pyro must do it. Not always, but regularly.

The second common way to detect a spy is running into him when disguised. You can pass through teammates but you can't pass through enemies. Enemy spies aren't an exception. If you can't run across a teammate, it's a disguised spy.

The third common way to detect a spy is tied to the previous one. Run into a cloaked spy makes temporarily reveal his form and often, the class he's disguised as.

You can also spot a spy when he is "yellow", in other words, well in TF2 words, he's been jarated by a sniper (who has thrown a Jarate). And don't think that being cloaked will save you if you're the Spy, you'll be revealed.

Also, when you're a medic, you can heal spies without knowing. If you have a doubt about one of your teammates, shoot syringes. If it's a spy, you will recuperate health points and a cross will appear above his head. Unfortunately, it's only working with the advance syringe weapon, as the normal one doesn't feature this capacity to heal from causing damage. Just for you to know, for unlocking this weapon, you have to unlock ten achievements in medic pack.

In the same idea, a spy can't shoot or he'll loose his cover. If a teammate seems not to be shooting, it could be a spy.

This one can only be working if a teammate is dead. If you know that he just got killed but see him running near you, well, it's a spy. Or if he's calling medic while the real one is dead.... I've already met this situation. The spy doesn't know in who he's disguised, so, he can't know that he's calling medic with a dead teammate's name.

This one is only if you cross the path of a newbie spy. Advanced spies will never do this mistake. If you see a blue ball or a red ball near dispensers, it's a cloaked spy. It can also be a teammate of yours, so tell him not to cloaked near dispensers or he'll be busted.

If you're engineer, hit everyone who is coming towards you and your building, it can be a spy. It's only working if the spy is disguised and not cloaked. Never stand still because you're the main target of a spy.

A medic is healing his teammates and also can provide ubercharges or kritzkrieg. But unfortunately, he's not protected by his team despite being helpful.

So here are some tips for being a good medic.

Combat medic
First of all, you can be a combat medic if you want. That means running into the battlefield and trying to kill enemies. But it's not well seen by the others, who are dying, burning to death or needing an ubercharge. If you prefer to kill, don't choose medic.

But even a medic has to be into a combat: spotting spies is a good way to switch in combat mode: shooting syringes or using your saw for spychecking will show to your team that you've spotted a spy and that you can go back to your job if they're helping.

Building uber: some tips
You can heal players with full HP but healing players with low health is more efficient for building an uber: indeed, the more they're hurt, the faster you will reach the 100%. Also, don't forget to extinguish a player burning to death.

If you see a fellow medic badly hurt, even if medic can regenerate his own health by letting time pass, don't hesitate to heal him. Sometimes, it can save an uber and it will help you to build one.

Some maps can allow players to build an uber elsewhere than in spawn without having to run into battlefield. For example, setting a sentry in the right tunnel in Dustbowl Stage 2, when you're going for the last cap point, is a way to keep safe players who will go through it for trying to cap the last point. Well, with the sentry as a defense, you can also build an uber in a somewhat secure place. You can ask a demoman or a soldier to hurt himself by putting stickies on a wall and making them blow up on him or by shooting a rocket in the wall while being next to it. As I've said, the more they're hurt, the faster you will reach the 100%. And building faster an ubercharge can be the key to success.

Which class to uber or to kritz?
Now, an ubercharge is a way to make invincible for a short time a player while healing him. You'll be also invincible during the time of ubercharge. But you must know that you don't uber like that. Not every class needs an uber.

For example, don't uber a spy, an engineer or a sniper, it's pretty useless because, well, you'll waste an opportunity to do some damage. And for the spy, you can reveal that he's one. Because healing a friend spy, who is disguised, is a way to reveal them to the opponent team. Never heal them in front of the enemies, just heal him when he's coming to you, burning or calling medic.

You can uber a medic who is at 100% of ubercharge, because after that, he'll uber you and you can be invincible for a longer moment. I've seen this tactic and I garantee you that it's disorientating you. But well, for me, you have to establish this plan with all the team and they must be ok with it.

You can also uber a scout, after all, there is an achievement for medic with scout. But well, it's not something common. The scout being faster than the medic, you'll loose him quickly.

The best classes to ubercharge are soldier/pyro/heavy and demoman. These players can kill quickly a sentry and when you're ubering an heavy or a pyro, it can do some damage to the enemies, much more than a demoman or a soldier. The ubered demoman is very useful for destroying sentries.

Don't uber too early or too late, even if sometimes, it's hard to tell when to uber. Just don't uber during setup time when there is one because you'll waste it for no result.

What can prevent an uber to do
Also, when ubered, you can't push the cart or take a control point. So, if for the capture point, it's not a vital matter, for the cart, it is. Don't stick with your partner that you've ubered near the cart, it will be a waste of time.

What a medic never had to do if he must uber
Also, never take intel if you want to uber. Indeed, you can't deploy it with intel on your back. And if you try to uber a teammate with intel on his back, you'll be the only one to be ubered. Intel is preventing any players to receive the previous charge.

Kritzkrieg: Difference with Ubercharge
With the medic pack, a new type of ubercharge has appeared: the kritzkrieg. With the krittkrieg gun, you can heal (and build) faster players and you're giving them while kritz only critical shots. The problem of kritz is that it's not giving invulnerability, so you or your partner can be killed during the charge and that it's lasting less than an ubercharge.

The pyro can airblast people or rockets/stickies/grenades by right-clicking when equipped with the normal flamethrower. It doesn't work with the backburner.

It can be useful for throw back an ubered pair going to your sentries or going to spawn point. Usually, the enemies are disoriented by being airblasted and aren't reacting quickly to kill the pyro, mainly if it's a demoman aiming for sentries.

Also, you can throw away stickies that are near your spawn points, on capture points or on cart for example. It's also a way to reach faster the Hot Potato achievement - several players think that the achievement can be only reached by airblasting soldier's rockets but it's more easy with stickies on the ground than a moving rocket when you're not used to airblasting.

The cost of it is 25 ammo, so, airblast only when it's helpful or else, you'll be quickly forced to take ammo pack or to retreat to the nearest dispenser.

There are several ways to reveal an enemy spy:

- Walking into a spy will make him translucent for a moment
- You can walk through teammates, but you can't walk through disguised enemy spies. Attack the spy if you come across him, as all he can do run away.
- Igniting a cloaked enemy spy will set him on fire and distinguishes him with an enemy coloured glow

Scout's are incredibly fast, but with 125 health, they aren't built for face to face combat. Go in, do damage and retreat!

When the lightning symbol is fully charged, a headshot to any class will kill them instantly. However, an over-healed heavy will live through a fully charged headshot.

Here are some tips to avoid some inconveniences. A spy is very useful when going behind enemy lines, unfortunately, there are a lot of ways to spot him. Some can be avoid, some not. Also, a good disguise is always a good advantage.

Chrome3 already wrote about disguises but it's only about heavies and scouts. However, some other disguises are not indicated. That's why I'm writing a passage about it.

Disguise
Don't disguise as an heavy or a soldier. They're slower classes and you'll adopt the same speed. Don't disguise as a medic. A real medic is always showing the % of ubercharge/kritzkrieg to his teammates. A spy disguised as a medic doesn't show this %. You can be easily spotted.

Cloak
When you're cloaked, don't run into a enemy. Not only he can't run across you but you will also reveal yourself a little. It will not take long before being dead. Also, don't try to shoot or to stab too early, don't forget that you can loose your cover once you're attacking.

Also, don't heal you at an enemy dispenser when cloaked, a glowing ball will appear and you'll be spotted.

Who to kill?
Try to get to players that can be good enough to make a massacre. For example, if a skilled sniper is shooting a lot of your teammates, try to get behind him and to backstab him. Or if a demo is having stickies on points and you've guessed which he was, kill him. But the two common tasks for a spy is to sap buildings and kill players with their medics.

As this passage about killing, I'll speak about players. Killing a duo with medic is something that a spy needs to kill. As you know, a medic is always following his patient. Begin by killing him first then kill the patient. Not only you're retarding an uber but you kill two players in a row.

Sapping
Sapping a building is making it out of service until it's blown up unless an engi is destroying your sapper. By chance, sapping isn't considered as attacking, so, you'll keep your cover. But don't kill engineer before sapping his sentry or you'll loose your cover and you'll be killed by the sentry, particularly if it's a level 3. Don't reveal yourself in front of a sentry, try to reach it by going disguised and if you're cloak, uncloak you behind the engi, not in front of him.

Also, you can do a naughty surprise to the opponents: if they have to do a long way in the map, between the spawn and the current location of the team (or the cap point or the cart), sap the entrance teleporter at their spawn.

(Requires any button[but best is one that is nearest movement keys] bound to choose last weapon) If you're about to sap engie's sentry and he's standing in front of it, disguise yourself (any class is good just make sure sentry don't kill you), take knife from your inventory (to choose knife as last weapon) and then take sapper. Stand behind engie sap sentry press the last weapon key and stab engie. I use this method and it works very well, even if i do it fast.

Do not disguise as a class that is faster than the spy. You will be noticed if your disguised as a Scout.

Note: if you disguise as a Heavy, you will slow down to the same speed as a Heavy