Before you send off to an editor or proofreader, why not make their job easier and appear more professional by weeding out simple mistakes?
1) Redundancies. Why say 'stand up' when you can say 'stand' instead? Another example is: she slapped him with her hand. The redundancy being 'her hand'.
2) Misspelled or misused words. The most common being where, was, were, to, too, of, off.
3) Overused words. Keep a note of words you notice are used frequently, search in the end and replace if necessary.
4) Avoid unnecessary adverbs. Why say he ran quickly when you can say he raced, galloped, zoomed, etc?
5) Use power verbs!
Don't say her hair was long and went over her shoulders down to her butt. Say it spilled over her shoulders, swishing at her rump as she moseyed by.
That isn't everything, but it's enough to help comb through your manuscript prior to sending it off to an editor or proofreader.
Good luck from Thomas Author Services!