Yes, you are a bad poster. And by “you” I mean you personally. However, if you follow these guidelines you may become a less-bad poster, which is something we look forward to with the utmost anticipation.
1. No antiquated terrible meme posting. These are memes that were potentially at one point effective and maybe even amusing, then discarded, taken up by CAOD, SHC, and posters like you, and driven into the ground. They are obsolete. At this point seeing “u mad bro” posted, or references to people “being mad,” is like listening to your grandparents use slang ten years out of date. It is wince-inducing.
2. Images you pulled off 4chan. Yes, we know 4chan is hilarious and the captions are soooo funny! Post all the pictures you want there! But post words here you fucking illiterate.
3. Various permutations of the word “fail” that do not adhere to classic, pre-internet usage. Likewise "epic." Keep that shit at home.
4. I heartily encourage you to lurk before posting. Lurking is useful because it introduces you to local posting conventions and generally gives you a handle on the regular forum denizens.
5. When you find a good post, take a few moments to examine it critically and figure out what makes it a good post. What makes it amusing? What makes it enjoyable to read? Do the same to a bad post. What makes it garbage? What makes it painful to read? Try to incorporate what you learned into your next post.
6. Along the lines of #5, study the good posters and the good trolls. Look at their language, their tone, and even their gimmicks. What makes them effective? You don't have to copy them, but pay attention.
7. Don't do emotes in a post. This isn't a Vampire the Masquerade RP room on IRC.
8. Recognize ironicposting and written sarcasm.
Unless you are confident in your command of the Art of Posting, I recommend being succinct. Writing long, elaborate posts is really only fine if you are confident in your ability to hold the reader's attention and keep them interested/amused throughout the length of the post. You remember that scene from The Shawshank Redemption where Tim Robbins had to crawl five hundred yards through a raw sewage pipe? That's what reading a long bad post is like.
This goes for angry rageposting too. I don't personally endorse rageposting because it is terribly boring, but some of you fuckers love rageposting like Suas loved cocaine. Whatever, I can't personally stop you. Just make it brief.
Posts about how awesome you and your legion of space badasses are and how you are about to rain rape and pit bulls onto your hapless space adversaries are also boring. If you post these, you will likely be trolled.
Don't get trolled. If someone posted something obviously provocatively wrong and you feel compelled to correct it and it wasn't posted by CrusaderKnight then you are probably about to get trolled. Looking at you, TEST.
Know when to get out of a thread. Threads usually degenerate into complete circular fuckery, and spending further time in that cesspit arguing is a waste. When it becomes clear that further debate is pointless, leave.