I've been playing for upwards of five years, somewhere around seven or eight years. I've seen some great games and I've seen some total flops. These are tips I've developed.
-Keep a file somewhere on each of your characters. If you want to be able to access it anywhere, get a Google Documents account and save the document online (http://docs.google.com). In this file, include your character's profile, a list of who your character has met in the game, and maybe what your character has done. I always forget who I've met or how they met in the long run. It makes a great reference.
-Remember the difference between IC and OOC. This is probably incredibly obvious. What you know, your character doesn't necessarily know. If a character really hates your character, that doesn't mean the player of that character hates you.
-When you're making a post, try to follow the skirt rule: Long enough to cover what it needs to, but short enough to keep it interesting. When posts are too long or too short, they're equally hard to respond to.