It never fails that people ask me what advice I'd give to aspiring authors. There is a LOT of advice I'd give to aspiring authors, but I'll hit some of it right now for you...
You and the editor are partners. The editor isn't trying to dismember your baby; she's trying to polish your gem. (That little quote comes from an editor I know, Suzanne James.) Sometimes, you have to cut the rough edges off of a gem before you get it to shine. (And, that clarification is my own.)
That doesn't mean the editor is always right, though. If you think the editor is wrong, discuss it. If it seems like the editor is asking for a LOT, for a complete change of premise or voice, talk to her and ask what the core problem she sees IS. Sometimes, a relatively small change is all that's needed to fill what she perceives as a large hole.
Don't get the EIC involved while any possibility exists to work out the problem between you. I've involved the EIC once in 37 books. I've been told I SHOULD have called her in for three other problems that I finally solved myself.
Writing is NOT the end of your work. You don't just sit back and watch the money roll in. You do edits. You market. Even the NY authors, unless your name is Nora Roberts or Stephen King, have to market themselves. Not all marketing costs money. Sometimes, it costs nothing but time and effort, but you have to market.
And, for the love of all that's holy, act professional. Don't make childish demands and expect people to bow to them. Don't play diva. No one likes a diva. Make requests respectfully and with good reasons why you feel something is appropriate and prudent. If it works out that there are factors you don't know about, take the loss gracefully. Don't stir the pot, make nasty comments about others, or otherwise show yourself to be a petty, unbalanced little creep. That's how you get yourself passed around as the author no one wants to work with...and that does happen.
Don't argue your "voice" and "artistic vision" as the end all of edits. There is a HUGE difference between your voice and poor grammar. Dialog is one thing. Writing an entire book in poor grammar is poor writing. The publisher has a minimum standard they have to hold for their existing readers. Messing with that is not going to win you brownie points.
Neither is refusing to change terms that the editor can prove to you are trademarked or copyright terms. I don't care if you DO like the term light saber. If it's trademarked, lose it and call it an ion sword or a laser sword or plasma sword. I don't give a crap what you call it, as long as you're not using a trademarked term...and neither does the editor. No brownie points for insisting on breaking laws. The publisher won't chance it, and they will insist you not. If you go unprofessional here, you're making a name as an author no one wants to work with.
Don't tell the publisher/editor that X-big-name author does it. Sorry. You are a newbie, who doesn't have a huge following yet. And, just because X-big-name gets away with it doesn't make it good writing. Not that I find Stephen King particularly lacking (at least not in the books of his I've personally read), but Stephen King could put a book out there in really poor grammar and sell it, because Stephen King wrote it. My first editor asked me, "Do you want to write a good book or a great one?" Great, and that meant not falling into the lousy traps that some big-name authors fall into and get away with.
Another piece of advice I like to give is that you can't BREAK the rules of writing that people hold to unless you're expert at it. In other words, if you can't handle the basics in POV, you shouldn't even attempt to break the rules set up for POV. If you are proficient at POV and can make the breaking of the rules seamless and smooth, if you can do it without throwing the editor or reader out of the book, you can "break the rules."
Oh, and if you have to ask me if something is working, you probably already have your answer; IT ISN'T. If you can't tell it's working, it's not. Something is wrong. You just don't know what is wrong yet.
This is a career. Invest your time in honing your craft and learning to speak professionally. Don't send an e-mail to a prospective publisher with IM-speak in it. You're a professional writer. Seeing something like "R U taking on new book?" does NOT inspire confidence in your writing abilities. Laugh at it, if you will. Whether your book is flawless (none ever are) or not, you are proving by that that you are not a professional author and don't take your writing seriously as a career choice when you choose to ignore professionalism in your querying.
For that matter, learn what the terms MEAN. If someone tells you to send a query letter, don't send a cover letter. If someone asks you to send a proposal, don't send just a synopsis. This is a career. INVEST in it to succeed.
Even when you have a publisher, don't get TOO informal with him/her. I send notes to my former EIC that say, "The computer's FUBAR. Can you resend the galley file for The Warrior's Widow, and I'll see if I can open it this time." We're the best of friends, so I feel comfortable sending that. BUT, notice that I identified PRECISELY what the problem was and told her what I needed in return. Sending an e-mail that says, "Jo, It's Sue. What is the problem with my book?" is a nightmare for an editor or publisher. Why? They may have ten Sues. Which Sue? Which book? What problem? A problem could be anything from a broken link on the site to cover art that is fuzzy to edits that weren't confirmed to be received to an ARC that doesn't show the final round of edits. You see the problem here?
But, professional or not, if I ever forget the fun of writing novels, you might as well shoot me. I don't want to do it, if I don't enjoy it.
Anyway, that's probably more than enough for today. Sorry to talk so long.