The Sims 3 Tips

The Ambrosia Recipe
Ever heard of the outrageously expensive recipe that costs §12000 known as Ambrosia? Ambrosia has the ability to restore the human form of a ghost Sim (only ones that are uncontrollable), it can increase mood by +75 for a week, and can make your sim young forever. Well, I can tell you how to make it!

Required Skills: Cooking, Fishing, Gardening.

Levels of skills:

Cooking: Mastered (level 10, must have mastered this skill to be able to read the Ambrosia recipe)
Fishing: (You can start getting catching deathfish around level 7 of the fishing skill, but mastering it is recommended, you catch them faster.

1 Life Fruit
1 Deathfish
Ambrosia Recipe known

Getting a life fruit is a taxing thing, but the results are well worth it.
If an Elder eats a Life Fruit, then they will live longer before dying of old age. They can still die prematurely, though.
You can identify a Life Fruit because they are shaped like pears, and they are cheery yellow. If you can see a halo around it, then you know for sure it's a Life Fruit.
You just have to wander the town for a while, harvesting every yellow fruit you see. You'll eventually find one.

Deathfish are blackish-blue in color, and they live in the pond in the graveyard of Sunset Valley. You only need one, but feel free to catch more then one for future use. IMPORTANT TIP: Deathfish can only be caught in the graveyard of Sunset Valley's pond between 12:00AM and 6:00AM! You will know you can catch them because there will be a thick fog above the deathfish. Fish in the fog.
The bait that catches deathfish is the Angelfish. The bait for Angelfish is the Alley Catfish (just buy some from the supermarket).
After catching some Angelfish, fish with Angelfish as the selected bait in the fog above the pond. When the fog disappears, you will have to wait until 12:00AM for it to appear again, and for deathfish to be able to be caught.

After catching some deathfish, buy the Ambrosia recipe from the bookstore. It costs §12000. When you get home, read the Ambrosia recipe. Then click on the 'Make Breakfast', 'Make Lunch', or 'Make Dinner' options. Select 'Ambrosia'. Your sim will start cooking it, don't bother the sim while they're cooking. When your sim is finished cooking, the Ambrosia dish is the mix of food that has a sparkly, rainbow-colored swirl to it.

Wait for an un-controllable Sim ghost to eat the dish. When they are finished, they will rise up into the air, an aura will sorround the ghost, and then they will be restored back to their normal form!

Ghost sims aren't the only ones who can eat Ambrosia. Normal sims can eat it too. They will get the "Divine Meal" moodset, which will increase their mood by 75 for a week. Eating it will also make a sim young forever! Be careful about which age you eat it at, I'm not sure if they can have birthdays and age up anymore.