1. It's fine to tout your wares, but throw some love to people who aren't you, too. When you link to your recent publication, book, or blog post several times/days in a row, I want to punch you in the neck. This isn't Blue's Clues, Narcissus.
2. Stop using the word slush. Stop saying slush pile. Especially if you're talking about submissions sent online. There is no pile. You're just being an asshole.
3. Some agents and presses only read queries sent by mail. Some are open to e-mail queries. Nobody wants a query sent through Facebook. What the hell is wrong with you? Why "friend" an editor or agent just so you can bug them about your manuscript? RIght, because insincerity always works.
4. You know what? There is no reason for agents, et. al., to not accept queries by e-mail. You sell eBook rights? You can handle Gmail. Put that Ivy League education to work.
5. I like you. I like your book. You like my book, too. Aren't we dandy? But if you send me another event invitation to a reading that isn't within driving distance, I will cut you.
6. If an editor specifically asks you to submit work, whether it's a solicitation or part of an encouraging rejection letter, send only your best work.
7. Magazines and journals should not charge writers to submit. A contest entry is different. A writing contest is a lottery for people who look down on people who play the lottery.
8. If your submission is accepted elsewhere, withdraw it from all other journals currently considering it. If a journal uses an online submissions manager, this is exceedingly easy. Don't write the editor asking them to withdraw it. If the editor writes you back and kindly and gently explain how to use the online manager to withdraw a submission, don't respond with, "Indeed, the world gets more and more social." Whatever that means, weirdo.
9. Nobody cares how many words you wrote today. "Wooooooo, I wrote 928 words!" That's what you're supposed to do, knucklehead. Nobody in the office is running around saying, "Man, I sent the shit outta that fax! Did you see that? Boo-yah."