Welcome Raefella!
I haven't run or played in a PbP here yet but I host a gaming forum at
http://headonastick.com/forums/ (it's a small group and spambots hammer it so I keep registration closed except for direct requests) and have GMed a few long-running games. I happen to have a job where I CAN muck around on the internets here and there, so my posting time is during work, when applications are compiling or at lunch and so on. I have no posting time at home. I use Google Docs to write up my GM-posts so if work intrudes, I don't have to remember to keep my posting window open because google saves my work for me. If by some miracle I DO get posting time at home, I can load up the same post and continue working on it. So having convenient tools at hand is important too.
Wiki's for games can really help. It's tedious to dig through all the old posts to find something.
Hell yes. I use a wiki for my game, and it makes keeping track of current FP a breeze as well as having a central repository for character sheets.
Most of my players keep in touch on google talk as well. If I see someone online and their turn has come up, I’ll ping them and remind them. I try not to be pushy; only after it’s clear the game is waiting on them and it’s been a day or so. Gtalk is also really good for spot-handling FATE Point expenditure and Compels.
It's all about routine, convenience, and mitigating expectations. To speak to that last point, I think for a while I expected to get the same experience from PbP as I do from tabletop. Maybe that's what turns off some PbP players after a while, the disconnect between what they expected and the reality of a PbP game.
1. There is no shared thrill of rolling the dice in a PbP. No table banter, no immediacy. Combat is affected most by this IMO. I can sit at a tabletop game, say "I hit him with my axe", roll some dice, and still have a great time with my friends. You take that into a PbP and there's no real choice for a player. The GM might as well puppet the PCs for all the choice they have. In a PbP the GM needs to make sure the players are making choices, not just reacting to skill rolls, and I think FATE works extremely well for this. You have to set up each situation so the tension doesn’t come from “will I make this skill check”, but rather “which path do I want to take”?
2. Expect players to put in less work than you as the GM. It’s just how it is. I’ve never had any luck with mysteries, unraveling conspiracies, or complex heist plans in PbP games. OK, honestly, I’ve never really had luck with those in tabletop either. The point is, PbP take a long time to get through and you shouldn’t expect your players to remember clues or NPCs from more than maybe a few weeks ago. You can run a game with a richly detailed backstory and four tens of major NPCs, but you need to be prepared to handhold and remind the players as you go lest it become overwhelming. It’s not that players are stupid, God no, it’s that we’re ALL lazy. If it’s hard work to juggle all the game info, it’s going to decrease the incentive for players to engage with the game.
3. Playstyle conflict. Any pick-up PbP will have this, I think. Somebody is going to join thinking it’s a game with X and find out it’s a game with Y and they’re going to lose interest. There’s nothing to do for this except recognize it as early as possible so you can go your separate ways.
4. Posting rates. If the group can agree on a posting rate (more or less), that’ll help manage expectations as to the speed of the game, plus you can call out slow players on the agreement.
5. Keep the game moving. I believe this is termed “aggressive scene framing”. Sure, I suppose there’s a use for loitering around in a scene and seeing if players will RP with each other. IME that generally turns into “nothing’s happened in that game for 3 days, I’m going back to Call of Duty.” Move your scenes like you were doing an episode of Law & Order. As soon as someone makes the last witty comment in a scene, just move everyone to the next scene. Keep giving your players something to do. Work on a post until you can get it to the point where, in a tabletop game, you’d be asking “what do you want to do?”
6. This is perhaps my personal hangups, but I don’t like to saddle players in tabletop OR PbP games with “helper” NPCs/GMPCs, unless those NPCs explicitly (say, due to military rank or something) are not involved in decision making. It puts the onus on the players and (hopefully) keeps them engaged, keeps them from falling back on the NPCs. The other thing you have to do, then, is to keep your OOC thread going. Don’t be afraid to infodump OOC and get the players what they need to make a decision.
7. I think what PbP does do well is immersion (as weird as that sounds). You don’t have the table banter, the weeks or months between sessions. The rate is slow but probably fairly constant, there is a clear IC and OOC split, and as GM you have ample time to plan the little details like NPC names, city details, and so on that might get joked-up or glossed over in a tabletop game.