ACCEPTANCE!
What can I say here, except that after you've shouted your happiness to the world, and have celebrated, you must come down out of the clouds and deal with the contract . . . and more revisions. What? You thought you were done writing your book? Think again, for your work may be just beginning! For this author, it was a joy to anticipate working with a 'real live editor.'
First, the contract. Book contracts for new authors and for established ones differ considerably. Items on a contract for a new author may not easily be negotiated, but nothing says you can't try. For an unknown, royalty rates are usually a good deal lower than for an author who has several titles out. There isn't much you can do about that until you establish yourself in the publishing world. (Assuming that established writers have gone beyond the need for this information, I'll deal with new authors.)
Having never published a book, nor signed a book contract, I decided to let my editor guide me. After all, Houghton Mifflin was a well-known, well-respected publisher. But looking back, I would have asked a contract lawyer to review my contract before signing it. Still, it was much better than I had hoped for (being new and green). I learned later that it was fairly standard for new authors. There were a couple of items I might have changed (such as the right to be notified that my book would be going out of print, and that I'd have the option to purchase remaining copies), but basically all was satisfactory, although a lawyer experienced in book contracts would have noticed that.