gbf
you need to read, read, read more scripts. can you imagine someone who says they're going to write the great american novel and this person has never even read a novel?! how absurd is that. find scripts that are similar to what you want to write: Welcome to the Dollhouse comes to mind b/c this dorky teen is obsessed with a cool older high school student and the audience understands her situation enough to laugh at her and feel sorry for her at the same time.
you can use an actor (like BMurphy) as a guide but know that by the time you're really ready to market your stuff that actor will be in a different place in their career (and much, much older).
you can put your script on hold by writing another (and maybe another) then you can revisit this one and decide whether its worth salvaging with a rewrite.
if you continue to write your writing will improve. i suggest you save that 90post thread about your crappy script and read it again in one year's time. you may be embarrased that you exposed yourself too soon (this kind of experience is priceless) but, you will be amazed at how much better your writing has improved. this happens to everyone!!!