baby steps
Don't worry about catching big air or power sliding through turns. Just get comfortable. There's really no replacement for time -- the more time you spend on the bike, the better you'll get on it. When you're comfortable at one level of jumps, turns, whatever, then push yourself just a little bit further.
You know how athletes practice specific shots, moves, or plays in slow motion over and over? That's to make sure they get the technique down first. Then they increase the speed.
The two biggest tips I'll offer are 1) Learn to brake -- front or back or both -- under any condition. Knowing you can stop when you have to will let you go faster. 2) If you feel like you're going too fast... you are.
Can also find some stuff at
dirtbikeblogger.blogspot.com
Welcome to the dirt chewing mob! (man I wish I could remember being 14) ;)