One of the scariest things about being a writer is being edited - especially if your work comes back with a ton of red ink on it. Here are a few tips.
1. You're on the same side. You and the editor have the exact same goal - to sell as many books as possible. A good editor will take the raw diamond of your story and make it shine.
2. Don't sweat the small stuff. If you and the editor have a difference of opinion on the Oxford comma...well.
3. Know when to stick to your guns and when to fold. If you're really uncomfortable with something an editor wants to do, tell them. In most cases, they'll respect that. (Not always, but that's another topic). Picking your battles will keep the relationship on an even keel.
4. Always be polite. Always. Even if they have you wanting to tear your hair out. Treat the editor as you hope they will treat you - with respect.