[nunoc]

Look at the guys that always win and do the same. If you are doing the same tacks and you still not doing any better, look at your sail trim. You would be amaized how many people forget to maxize their trim because they are too focus on the course.

Well, those are my two cents. Personally, I try to do as few tacks as possible, since you can loose as much as 15 secs to a min by tacking, and in the class I race, the difference between first and 5th is usually around 10secs, after adjusting (PHRF A)