I sprung for the D300 a frew months ago and am still on a fairly steep learning curve. I read the manual, which I didn't think was very good. The DVD that I purchased was much better. I visited some photo forums and got a few suggestions for a bank of settings that would be good for bird photography, and through trial and error came up with my "standard" settings, which I use 90% of the time. I use shutter priority set at 1/200 sec., spot metering, single point auto focus, always in VR. This lets the ISO go (set at 400 min.) where it needs to once the aperture is maxed, as noise is not a big problem til it gets over 1000 (I have gotten some good shots all the way to 3200). My current "bird glass" is a Sigma 150-500 f5--6.5 lens, but I'm lusting after something faster already.
Since I don't shoot every day, I don't think I'll ever completely master the camera. I was a confirmed Canon user before I checked out the new Nikons, which now IMO are on a par with Canon and in some ways superior (I threw that in just to get some argument from the Canon people!)
Twin Lakes Ranch
Central Texas