Correct Point of View: Omniscient POV is no longer acceptable. Quit using 80's authors as models.
Promotion 101: It takes an average of 10 mentions of your name/title for people to go (head slap) You wrote that? I've got to get it! Know your pitch; keep it brief; and get out there and sell yourself!
Read Submission Guidelines Thoroughly: Yes, there are publishers out there who will automatically reject you if your subb is sent in the wrong format/you didn't use 12pt font/you sent it to the wrong editor/called editor 'Editor' (or wrong gender)/simply wrote 'Here's my submission...' If a friend sends you a head's up call, READ the guidelines, even if they are spelled out in the email? She may not have included everything.
Know When (or Where) It's Okay To Post Excerpts of Current WIP: Especially if it's uncontracted. Some publishers consider posts 'already published'. (I'm still figuring this one out.)
Know When To Shut Up About Your Work (directed at my alter-ego): Not everyone will be interested in hearing about ALL your books. Know when to recognize the signs you're boring your audience.