There are two kinds of stickers that you should try to avoid. The second kind are those that support bands that may provoke a cop to make assumptions. While this is grossly grossly grossly unfair, Grateful Dead and Phish stickers catch a cop's eye and usually lead them to make assumptions about drug use. If you choose to leave these stickers on your car, just know that you might have to fight the assumptions they produce. Most police departments treat traffic tickets on a quota system.
Some departments even award the officers who give out the most tickets in a month.
This means that there are some times of the month when you are more likely to get a tickets. So, the safest day of the month to travel is around the 15th. Also know when police duty shifts change. The best time to travel is about 30 minutes before such a shift change. Rather than calling the police station and telling them that you need their schedule so that you know when you can make an illegal U-turn, read the accident reports in your local paper to find out a police officer's name.