Assume people are looking for a reason to reject your story, and don’t give them one.
1) Get professional tools—Webster’s Unabridged, Word spellchecker, and a Chicago Manual of Style 15th edition (used), minimum. For basic dialogue/comma rules Strunk and White, or grammarbook.com will help.
2) Polish the first three chapters till they squeak—no one will read past “It was a dark and stormy night”. If you have to tell us “It gets better later,” then rewrite.
3) If it doesn’t pay rent, cut it—Stephen King cuts 10 percent of each first draft. Any word that doesn’t need to be there or scene that doesn’t further plot/character/setting, remove. Write a one page summary of your story to help decide what is important. Publishers have a limit of about 80K words for first books, slightly more for fantasy.
4) Read your book out loud, especially the dialogue—as a side-effect, you could create a Podio book episode of two as advertisement.
5) Write a killer pitch to sell the story—if people won’t grab a free copy when offered, you’re doomed. This will take 20 or 50 drafts.
6) Get a professional cover—or no one will read your pitch. thecovercounts.blogspot.com is inexpensive and quality.
7) Get criticism from someone not related or your friends—repeat four times. For those without crit circles, start on authonomy.com in the Brutally Honest Criticism Group.
8) Get a professional to edit—nothing gives us all a bad name like a simple mistake.