Heads Up Strategy

I recently have been coming in 2nd a lot in my tourneys, live and on the internet, and I was just wondering what I can do to improve my heads up play. I'm aggressive and bet at a lot of pots but it seems that i steal a lot of small pots, but my opponents win the big ones that cripple me usually. I know im better than a lot of them but can't seem to beat them. I also get impatient a lot which is a terrible thing to do i know, please any advice is helpful.