I remember from the days before I was a cyclist that knowing how to drive around us can be confusing so here is a basic question one can ask him/herself when driving in the proximity of bikes: how would I treat this person if s/he were in an automobile? Would you pass a car and then slow down in from of them to make a turn? No, so don't do it to a cyclist. Would you pass a car when immediately approaching a stop light/sign? No, so don't do it to a cyclist. In general, treat cyclists like cars. This does actually work both ways; you should expect bikes to behave like cars. If you see cyclists running a red light/stop sign or turning without signaling, by all means, report them and/or let them know how you feel! They're making the rest of us less safe.
There are, however, a few exeptions to this rule, the first of which is never honk at a cyclist. Your horn is very loud and scares the shit out of us so unless you want us falling off our bikes in front of your car, don't do it.