When to Post
If there are a few people posting in a thread, make sure to give everyone a chance to post. Post whoring, that is, posting quickly with one or more people so that other's don't have a chance to catch up or interject, is very damaging to a RP. For one, it can turn people off from joining a RP and it makes people more likely to skim over your posts, esspecially if they don't move the plot foward and take up mulitple pages. A good rule of thumb is to limit yourself to two or three posts of yours to one of someone elses, so you don't overload the people who can't post as often. Also the more people in the thread, the more chaotic it gets and the more likley people are to post whore, so please be careful, particularly in large storyline threads.
