It is a truth universally acknowledged, that a writer in possession of a rough draft, must be in want of an editor.
This is true no matter who you are, or how long you've been writing. I've gone through the stage that it seems every writer does at some point, that the first draft must be absolutely perfect or else the story is a flaming failure. I've backtracked and edited and second-guessed myself before I even have the first draft done, and what has it gotten me? A whole lot of frustration and a lot more unfinished rough drafts.
More recently, I've reached a zen-like state of serenity in the acceptance that my rough draft might suck, but it will be done. I write that sucker as it comes and don't worry that this or that scene doesn't make sense or oh wait I need to set up this plot thread earlier on or this guy's dialogue doesn't fit his character or SHUT UP ALREADY.
Yes, I grab that yammering little Inner Critic by the collar and tell her to eff off. Why? Because the rough draft is where the Inner Writer spreads her (or his) wings. You have an idea. Awesome. You have a fully-formed idea that could be a pretty damn good story. Even more awesome. You might even have the time to write the silly thing. Beyond awesome. But if you spend all your writing time backtracking and fixing things, your Really Awesome Idea will never see the light of day.
So what if your first draft sucks? It's supposed to suck. The rough draft is where you vomit out your raw idea just to get it on the page (or screen, or whatever). When it's done, you'll be able to step back and look at how the whole story has turned out, which will give you a better idea of what things really need to be fixed.
Every professional writer (with fewer exceptions than you might think) has an editor whose job it is to get that rough draft on its way to public viewing. Even they might have sucky first drafts. There's no shame in it. Get that draft completely out of your head before you start editing and tweaking. You'll be tempted, believe me--the age of word processing programs has made this stupidly easy--but you'll feel a lot better once you get your rough draft out.
It's what you do with your sucky rough draft that will let your story really shine.