Write another.
Seriously. Best thing you can do is start on your next thing. Two reasons:
1. Your first script is probably terrible. Most people's are, don't worry about it.
2. You don't want to put all your eggs into one basket.
When I pitched my "perfect" script to someone with the power to get it made he told me, "It's okay. But we just did a road movie. What else you got?"
I didn't have anything, and lost out on pitching a pretty big-time producer something he might like because I had put all my eggs into one basket, more or less. So, best advice is to have 3-4, ideally 6 different screenplays/treatments kicking around at a time. Throw them all at the wall, see what sticks-
Any questions, ask away-