There will almost always be someone faster than you, so don't beat yourself up if you make mistakes. Learn the track and try to be consistent. At that point you can make adjustments accordingly.
sometimes going slow is actually going faster through the corners... if you enter the corner too fast you will scrub off all of your speed with understeer.
Most of all have fun and make friends with the other guys out there. you will learn a lot about how to control your car, especially in the wet.
I wish I was going racing this weekend... but I'm always booked solid.