Until you get good at coming out of the gate, I would either take a gate at the outside end (probably the right side if they haven't changed it), or position yourself with a gap on each side of you (if the gate isn't full). If you do get a poor jump out of the gate, the riders on each side of you will close in and pinch you off.
If you're up front (top 5) going into the first turn, the inside line will probably be the fastest. After that, people tend to bunch up and you can probably pass people on the outside (especially at Dirt Country).
As is the case when you are practicing, if you don't double something, hold a straight line so someone doesn't land on you because you moved under them. (On the Gravity Cavity, I'd take the far right on the inside since people doubling have too much speed to cut back inside.
Don't ride over your head. You can't pass anyone while your bike is on top of you. :) Also, picking up the bike is worth a half a lap of energy.
In between races go out and look for the smooth lines...DC will get some braking bumps going into the corners.
and lastly...make sure you post a race report afterwards!