How do you guys get your shots?

I quite like street photography but I often worry about negative reactions to taking photo's of random strangers without their permission. I've occasionally turned my camera on people of interest in the past and received negative looks. Due to this I have a tendency to pretend that I wasn't trying to photograph them and I sort of keep turning the camera to point it at something else. Even if I did take the shot, I imagine it would be ruined by the subject glaring straight at the camera.

My question is, what sort of focal lengths do the street photographers on here use and do you ever get negative reactions? How do you avoid getting constant photo's of people looking annoyed?