The core rules of the internet is the rules that everyone should follow, the netiquette.
http://www.albion.com/netiquette/corerules.html

Role playing can be a lot of fun if you try and do it the right way. Try to make each post help the story, and trying to make sure that is looks and sounds good at the same time. Here are a few tips that should help you out.

Context
Context is a very important thing when it comes to role playing on a forum like this. Even if it is your character, it doesn't make it based on you. That means, if your character sees someone they won't just know their name. They must find it out, by asking or anything like that.

For example, if your character walks into a tavern , they won't instantly know what's going on. Your character has to learn, as well as you.

Replying
If you are role playing with someone, try and keep up with it. Avoid leaving it stagnant for a few days as that can suck out the excitement of it. Refresh the page every now and then to see if they have posted, then reply. But make sure not to spam up the board, replying before the other person has even had a chance to. Remember, there is a posting order that needs to be followed and double posting is not allowed.

OOC Chat in RP
When you're role playing, please try and keep the OOC to a minimum. The exception to this, of course, is Did I's, though they are technically related to the IC actions and so could be considered IC. If you do need to say something OOC, put some sort of thing showing that it isn't part of the game. Like brackets, (( or something of the sort. Generally, the RP area is for IC stuff, no OOC save for Did I's. Go to the General Nonesense board for OOC fun.

Interesting and Building Posts
When you're role playing, try and make your posts interesting and build onto the RP. Make your posts detailed, make the other person interested. We don't want them falling asleep. Maybe describe your character's feelings, thoughts, or your character examining his/her surroundings. Describe everything in detail, it will make it much more interesting. Don't just post meaningless or fluff-filled posts, make sure they mean something.

God-modding
DO NOT AT ANY TIME GOD-MOD! God-modding is a way of making your character invincible, such as not letting them ever get hurt. Even if your character is a fierce warrior, that doesn't mean that they can dodge any attacks that come at them. If you think you might be God-modding, chances are that you are. Just keep a level head about combat and you should be fine. Did I's will help prevent God-modding so use them!

Third Person View and Tenses
When you're role playing do it in a third person view. This means that you describe your actions with, 'he' or 'she' instead of 'I'. This makes it easier for some to understand. In addition, we'd prefer past tense but you may use present if you'd like. However, you must stick to one tense--don't go changing tenses mid post as that can be confusing and frustrating to those reading it.

Punctuation and Spelling
When you're role playing, use proper punctuation and spelling. This means using periods and such in the appropriate places, and also using a spell-checker if you need it. There's no excuses for misspelled words and bad grammar as you have access to the internet and all the resources attributed to it including the all-powerful spell-checker.