Metal Gear Solid 2: Sons of Liberty HD Edition Tips

Dog Tags
During the game, you will find dog tags that are awarded for holding-up enemies. If you gain enough dog tags, you'll gain rewards.
So, in the Tanker, gain 46 dog tags (30%) and you'll gain the Bandana.The Bandana gives Solid Snake unlimited ammunition when it is selected in his item list. Next, you have Stealth that is unlocked at 78 dog tags (50%). This will make Solid Snake invisible to all enemies (in the exclusion of Bosses). It is deactivated and unequipped when you bump into an enemy.
In the Plant, it starts off with the Infinity Wig that is unlocked at 73 dog tags (30%). This has the same properties as the Bandana. At 121 dog tags (50%) you unlock Stealth. At 170 dog tags (70%) you unlock the Wig B, that gives you unlimited grip. Finally, at 218 dog tags (90%) you unlock the Wig A, that gives you unlimited O2 when swimming.
Obviously, sneaking up behind almost all enemies in the game can be a bother as you can easily be heard or spotted. This can be avoided easily though in the Plant from when you get the Coolant Spray onwards.
First, tranquillize all enemies in the area. Then, approach whichever soldier you wish to search. Then, whip out your Coolant to wake them up. It is easier to do this when the enemy is facing you as it can be tricky getting into their view. After waking the enemy, he will stay on the floor for around two seconds, holding his head. Use this time to take out your SOCOM and aim it at him. When he gets up, Raiden will yell "Freeze!" and the soldier will raise his arms. If the soldier is reluctant to hand over his dog tag, you may shoot him once in the arm or leg and then aim at his head again. This will always work and although it is slow, it is safe.
To stop the annoying procedure of searching the same guard twice, equip the camera when looking at an enemy and hold down Triangle. If you have the guard's dog tag, his name will show blue above his head.
NOTE: You cannot obtain dog tags from reinforcements or from the Arsenal Tengu.