wetsanding the headlights is the best method in my opinion. I was buying nasty yellow headlights on craigslist for $40. and restoring them then putting them up for $150. a set. 600/800/1000/2000 grit wet sand paper. must always go opposite direction when doing so. then follow with ScratchX 2.0 and then PlastX...I do this on my aveo now too. Here's the actual right up I follow

How To: Polish the Headlights

the headlight on the left used to look like the one on the right. when wetsanding headlights if they start to look worse than what you started then your doing it right...