As a bicyclist for 15yrs and a motorcyclidst for 25yrs, the best advice is "always assume all vehicles do NOT see you". Regardless of your rights to be on the road as a bicyclist, always be careful and keep your perimiter in check and have an idea of an escape route if and when necessary. Hey - when it is a bicyclist against a cage or any other vehicle ... guess who loses that battle.

A mirror or two (handlebar, helmet, etc.) is of utmost importance if you plan on riding on busy roads. As someone else said ... some times, you may need to make a decision that a particular road is simply too busy and dangerous to travel.

Be careful, safe, and have fun!

Edited for superior spelling!