Quoted from BerkaZerka:
"Running a Forum Game is at least 10 times harder than playing in a Forum Game. The time and attention it demands can be overwhelming. I certainly don't recommend anyone try to run more than 1 at a time (unless they have considerable experience in doing so).
Perhaps the greatest challenge with running a Forum Game (most especially with RPG types, is keeping the pace. Nothing kills a game faster than a time lag (look at that awesome Cthulhu Horror Game that was going great... and then Blamo! a big lag and it was DOA).
Some tips for a Successful Forum Game:
1. Preparation. Know what you are going to do, the rules, and general direction the game is supposed to go in (all before throwing down a sign-up thread).
2. Never place the continuation of the plot on a single player; as inevitably, he will suddenly not be around to post when the story needs him the most and you will create game-killing lag as you wait for him. Be prepared to GM override a character to avoid this - but try not to get into that situation in the first place.
3. Follow a consistent Time Schedule and live by it. To keep your game floating, you as the GM must update it constantly (or at least every 12 hours or so). If your characters have a set posting requirement, enforce it. Do not be a nice guy and wait for anyone (see rule 2 above) - but set this, and how it will be handled, out in the rules before the game even starts.
4. Be adaptable. If something is not working, hash it out with the players in your Rules/Out of Character thread and go from there."