Well this past saturday I played in my first USCF Quick Tournament(G/10). I thought I was going to do well but I think arrogance gets the best of some people. I placed 29th out of 40. My last round was against a 9 year old with a whopping rating of 685(quick) and I beat him badly in one game, but blundered a way a queen for a pawn in the second game. The USCF hasn't given me my provisional rating yet and I'm getting really anxious to see what it is considering I've never officially had a rating before.
All in all, don't underestimate an opponent who is much younger and has a much lower rating than you are expected to play at. You never know what's going to happen in a blitz game. I learned my lessons saturday.