Originally Posted by
Coluber42
Another thing I think is useful, whether you use a mirror or not, is looking over your shoulder. Aside from seeing who's behind you, humans respond subconsciously to other humans turning to look at them..
Can't stress that enough. Regardless if you've already looked in the mirror, look over your shoulder too and signal. You should do the same thing driving BTW. The action of a cyclist looking over the shoulder makes a big difference between the impression of behaving responsibly or cutting the driver off.