Elliot Bernstein , Aug 22, 2008; 10:13 a.m.
The D300's focusing is one of its best features.
As a starting point, I would suggest you start learning how it works by just using the center point with the continuous focus mode. I have successfully used the 9 points cluster but generally stick with the single center point for fast action sports as long as I can track the subject.
I personally have not found the 3D focus tracking to be beneficial on the D300.