Signal when you change your "line"
I signal a left turn with my left arm and right turn with my right arm. I signal all changes in my line. Ex: If I'm to the right in a lane and plan to move over to the middle or left portion of the lane I signal my line of travel change. Then I signal again for the left turn if I'm turning left. The drivers actually get this and don't try to pull around me.
Also, I find it helps if you don't coast in traffic. The drivers seem to think they can beat you no matter what if you are coasting. If you are pedaling they seem to be more patient because it seems like you are at least trying to get out of their way quickly. Make sense?
As we must account for every idle word, so must we account for every idle silence." ~Benjamin Franklin