Am Editor's Checklist, and what to do about it:
1) You're over-using "and," especially as a sentence connector. Remove it and your work will sound much more dramatic and direct.
2) You're making em dashes wrong -- they're like this, not -- like -- this -- or any other way than -- this.
3) It's "Fred said," not "said Fred." "Said Michael," "said Jane," will make your writing sound sing-songy and biblical.
4) You're confusing "its" and "it's," and, no, it's not alright just because they're confusing. They're not: "It's" is short for "it is"; "its" is a personal pronoun, as in "the bicycle, down to its hubcaps..."
5) You're using "parent's" as a possessive plural, when it's singular. Instead, use "parents'" as in "my parents' house."
6) You're confusing "lies" and "lays" and, no, it's not alright to say, "She was laying with him on the bed." Make Fowler's Modern Usage your bedtime reading along with Strunk & White's The Elements of Style.
7) You're allowed one adverb per hundred pages. Search and destroy the others.
8) Remember to show us what's happening in your story, not tell us about it.
9) Your dialogue isn't action that moves the story forward. Root out every piece of dialogue that doesn't contribute to the forward motion of your story.
10) You overuse certain words -- you know what they are. Become aware of them, and don't allow yourself to use them more than once in 10 pages.
11) Your story doesn't really take off until page x. Remove the pages before x.