How not to scare away your hummingbird for the shot:
1. You should be in place for a while, maybe 1/2 an hour. (Think comfort, shade, chair, tripod)
2. You will hear your bird approach, it will make a sort of slurp chirp sound. When you hear it or see it in the area, move your camera to your face.
3. It will come to your feeder, the one you have pre-focused on.
4. Of course, when you see it in your view finder just press the shutter.