- Comunicate. This is sort of a blanket rule that I think a lot of things can be squished in to. Motion to drivers when you're going to be going into their lane. Shout that you're about to pass another biker. Make eye contact with drivers, pedestrians, anyone who's path you may cross who you want to make sure they know you're there, try to make eye contact. Smile and say hello to people who can hear you. Just for fun.
- Lock it up. Properly. Get a big old hefty U-lock. Find either a bike rack or a tall pole to tie your bike to. If you choose to lock it to a parking meter then the more power to you, but be sure that your lock dosen't allow the bike to be lifted over the meter (learned that one the hard way. When you lock up the bike you want to make sure that both the frame of the bike and the front tire are included with the lock. If you know how, then for extra protection you can pop the front tire off the bike and then lock that, the back tire and the bike frame to the rack/pole. I've found that back wheels are much more difficult to take off and are less prone to being stolen.
- Put your phone/keys/other things likely to fall out of your pocket in your bag. There's nothing worse than your phone falling out of your pocket while you're riding down a busy street. I've had it happen to me a few times, and while nothing's broken yet, it's still very inconvenient. Backtracking means you loose momentum and time. No one wants that.
- Know where you're going. I think this may be the most important thing of all. You do not want to be stopping in the middle of traffic to try and figure out if you're supposed to turn or go straight. You don't want to find out at the last second that you were supposed to be turning left up here, and should have gotten in the turn lane half a block back. If I'm going someplace I've never been I study the map carefully and then draw my route on a post it and stick it to the handlebar for reference. Works every time.
Those are the rules I go by though I'm sure there are others. I've also just gotten a bike check up which has helped my bike emencely. My new favorite thing, now that I'm riding fairly regularly in Chicago, is riding under the El. When I come to a stop light I use the El support beams for balance so that I don't even have to put my feet on the ground. It's like a game for me. Riding over the Chicago River is fun too. A lot of the bridges have only grates as the street over the river so you can look straight down into the water.