
After time, plastic(acrylic) headlights cloud and yellow, here's a quick and easy way to remedy that.
First, make sure your headlights are very clean, shit, wash the whole car, it definitely won't hurt anything.

See how clouded that is?

Gross!

Okay, so now you're ready to begin.
You'll need:
Regular nail polish remover. Acetone-free will not work, so dont get that

Metal Cleaner, don't use this kind, it sucks

Automotive scratch/swirl remover, and wax, I got an old bottle of combo crap, that worked great

and Rain-x if you feel so inclined
Alrighty...
First, get a cotton ball, and soak it in the nail polish remover, go to town scrubbing the bejesus out of your headlight. What you're doing is taking off the top layer of acrylic, that's gotten all cloudy-looking. THe cotton ball should turn a yellowy blackish color.

Here's the difference between my acetoned headlight and my old poopy one.

Once your headlight dries, it should be all cloudy, and freaky looking, like you ruined it. Put your emotions in check, refrain from yelling obcenities, and continue on.
Scrub your headlights with the metal cleaner. scrub like you've never scrubbed before. Clean off the metal polish as reccomended. Then you're ready for the wax. THe purpose of the wax is to fill in all of the little hole thingies left from the Nail polish remover, and metal polish. So, wax, and if you like, rain-x your headlight.
Here's the comparison for ya:
Before:

After:
