Ahh, intercollegiate shows. I went to the university of Findlay for western, so I know what you're talking about. (Good show program, HORRIBLE COLLEGE and teaching. ugh.)
Push your thigh down; that will help get that almost-straight-legged look and keep your heels lined up with your hip.
Keep your right hand (the non-rein hand) down closer to the pommel of the saddle, near the horn. Don't touch! Just don't bring it up so high.
Rein hand: Unless turning, thumb up!
Shoulders back, girly. ;)
Other nit-picky things that Findlay did:
Try to get your hat shaped, and ask for the 'quarter horse' style. Your sides aren't as sharp as they need to be. This is what the judges are looking for, and helps create the picture of a neat, crisp rider.
I know not everyone has the money, but if possible try to get a black shirt that has a color/detailing at the shoulder. The black shirt will help create a nicer silhouette rather then the red shirt that seems to cut you in half where it meets your black chaps/pants. Red+black is fine in a pleasure class, but not so in horsemanship!
Earrings, for when your classes get more serious (like open, etc.) and brighter lipstick. It's kind of like putting on stage makeup--it may look ridiculous to you, but the judge will hardly be able to tell.
Try to make the number on your back as SMALL as possible by either cutting off the excess white, or folding back the extra, and then use two pins (on the sides) to secure it--that way, it won't flop. (I didn't see it flopping, but I can't tell how you pinned it, lol!)
Whatever I can tell to other schools to make Findlay lose, I will. ;) Horrible training program for 36,000 a year.