MikeR's got it down. I also make a point of it to try and make eye contact with drivers as much as possible. For instance, if at an intersection, I'll turn around and make eye contact with the driver, so when the light turns, he'll be more apt to be cautious and give you the room. If on a straight away and you feel traffic is getting closer (group think), slow and turn to make eye contact with the next car that's behind you. Of course, make sure there's nothing dangerous in front before turning your head!!

And hand signals, hand signals are soooo important.