Wash your tail lights thoroughly and concentrate on one light at a time.
Mask off all painted surfaces around tail lights with painter's tape and scrap newspaper.
Use 2000 grit sand paper to sand the whole tail light. Work on a small area at the time and be sure to be very thorough.
Now, grab a can of VHT Nite Shades coating and apply it on one tail light at a time. You should apply it from about 10 inches away.
First, apply a very thin coat to each tail light and let it dry.
Apply the second coat in the same fashion.
By the time you finish, you should apply around 5 coats of paint. You can do more than that, depending on how dark you want your lights to look. On my Toyota Corolla, I used about 5 coats and the lights came out to be a little darker than original. The key is to apply coats slowly and uniformly.
I've heard that some people apply clear coat, but I never did and my tail lights came out just the way I wanted. It is a matter of personal preference.
If you are unhappy with the results or get tired of the look, you can easily return your lights to the factory condition. Just follow the steps, found in my article about proper headlight restoration.