1. Use proper spelling and grammar.
Use basic sentence structures with capital letters at the beginning and punctuation as necessary. Try to avoid needless abbreviations (like those used in l33tsp34k or however you spell it). Don't capitalize all the letters in word if you're not using them for emphasis. Just try to be as readable as you can. You don't get any points for typographical style here. Also, we assume English to be your first language, but if not, please inform us somehow (like in your profile location) so we know to allow for exceptions.
2. Don't chastise people for not having perfect grammar/spelling.
Although we want you to try to use the best grammar/spelling/punctuation you can, no one is perfect and we all make mistakes. Don't grill someone over it because chances are you're not perfect either.
3. Avoid pointless replies.
If all you have to say is a short affirmation("I agree", "You're right", "

4. Do not quote needlessly.
If you're going to quote someone's message and your reply only pertains to say, one paragraph out of a 20-paragraph message, just trim it down to the part that relates to what you are talking about. Be careful not to trim it down to the point where it seems out of context however.
5. Post descriptive subject lines.
Post more than just "Heeeeelp me" or "Have you ever..." or simply the name of a show. Make your subject lines as descriptive as possible, especially if you are asking a video help question.
6. Necroposting.
There is a difference between reviving old threads on purpose and doing so by accident. Most of the accidental ones occur because the users themselves are new. In that case, EVERY thread is new and so they shouldn't be raked over the coals because of it.
What else should there be in here? Or what changes to the ones I've listed?