Choosing a good route is probably the best advice. It does not have to be the fastest or the most direct route, but it should be the safest (for you). If that means you have more stop signs or stop lights plus more time added to your commute; but you encounter less traffic, less hassle, and less people trying to mess with you, then its a sacrafice commuters have to make sometimes.

As far as car doors go, ride about 3 feet away from them. I also check through the back windows when approaching (if possible) to see if their is movement inside. Doesn't alway work, but it helps.