I like to set my camera w/flash on a tripod, then focus in on where the bird will be (feeder or flower) then turn on manual focus. I then sit inside with my remote shutter release and shoot them as they come in.
After a few minutes they do not even care about the flash.
A buddy of mine has a great pic of a hummer, while I was waiting for a hummer to come to the feeder so I could get a shot the little bugger actually landed on my camera. I still think that hummer was mocking us.
LOL