Any BIF shooters?
The first thing I would do is to check that there is enough speed so put your camera in S mode select at least 1/1000s shutter speed, is there is not enough light, then put auto-iso on. Disable the VR on the lens and use only one (center) focus point and AF-C mode. Once you had got a couple of sharp shots, then try playing around with different autofocus settings. Put your camera left dial also in CH. Another trick is to start focusing the bird at 70mm, without taking any photo but just keeping the shutter button (or AF button) pressed at half, when the bird gets closer, still keeping the shutter button pressed at half, zoom in and then start the burst.
Good luck, don't experiment too much with the autofocus settings in the beginning, as you will loose time and patience, also the key is the shutter speed, at least 1/1000s.
A couple of pics with the D200 and the 70-300:
My photos: http://www.flickriver.com/photos/danm_cool/
My gear : Nikon D200 with Nik 17-55mm f/2.8G ED AF-S DX