Well how to start.
1. Don't be an @$$ ^() ||when you're riding, much like cars must share the road so must cyclist.
2. Always be on alert for cars, pedestrians, dogs, or other rodents, including cyclist who perform crazy Ivan's at random time intervals.
3. Take the lane, if the shoulder or non-existent bike lane is not very good just take the lane so you are seen and don't end up back in front of a car un-announced by a bad patch of road. Move smoothly and efficiently, don't flounder in the lane or they will attempt to pass you or worse.
4. Make your moves in traffic obvious, moving to the right to turn right, moving to the left to turn left, no sudden random turns or talking with your hands in random motion as you ride.
5. Look before you move/turn! No one is your babysitter, which means you have to be your own babysitter and take charge of your riding.
6. Trust no one, even a fellow cyclist who will take you down or into a bad situation by following them blindly. Sure if its a buddy you follow but still don't trust them, you never know when they are going to lose it (mentally) especially if they crash often, exceptions are made but don't let it be your last.
7. Stay away from know crash-ers or riders who behave badly in traffic, as in; yell at people, cuss at cars, spit at cars, etc. they just aggravate the situation and if you're close by you're included in with them, accident or ticket.
8. Don't give attitude, if a car cuts you off or other just wave and smile as if that was a friend. Some drivers end up apologizing because they end up thinking you know them in some way.
9. (USA biased, otherwise left for UK, Aussies) If you're at an intersection and cars want to turn right (behind you) and you're going straight give them room to pass by, if the light is red no one in the right lane is going to have an issue with you waiting in front of them as long as you move to the right when the light does turn green.
10. Look! I said that already but you must look no matter where you're riding, some cars are quieter than you think and you really can't let your guard down.
11. Stay away from buses! If you must pass them make sure to get to the left most so the driver see's you, or hopefully see's you. If you ride that particular street often, don't be a tool and ride in the known bus lane/stop if you don't have to, remember the first part of this one, stay away from buses!
12. Learn to look back without moving in that direction as well, takes time but you must do it. Or end up getting hit when you look over your shoulder to see if there's a car and yes there's one there coming fast right next to you and you just ended up in front of it.
13. Don't do anything dumb or stupid, or it maybe the last thing you do. If you see a friend there is no need to over wave hello or look at them till they vanish from the horizon, big smile and a wave no need to make eye contact for an hour. If you see some quality eye candy, well then stop, its worth it, but no need to die for it by ogling too much and doing something dumb, I know its hard not to.
14. If you break the law, expect the consequences and don't whine about it if you get the consequences of it. Who cares if so and so do it, or got away with it, or a warning, you got a ticket, suck it up. Don't want a ticket, don't break the law or learn to work with its fine nuances.
15. Lastly, have fun, you're out riding a bike instead of caged up somewhere.