Well I'm about out of advice but I thought since I mostly run D&D and it's a fairly popular game that I would do one game-specific post. As always, take this with reservations as I'm not in your band. I can hit the high points here though:
First: Which Edition? - You may have heard something about this on the internet, and it's true - people care about edition differences! There are really two approaches:
- Pick the edition you want to run, be up front about it, stick to it, and only accept players who want to play that version. The upside here is unity, the downside is that you may not find enough players to make a game of it.
- See what most potential players want to play and run that. The upside is that you should have a big enough group to get the game going but the complication is that you have to be willing to run that set of rules.
Second: Published Setting or Homebrew? Even if you get the edition right some people hate some of the published settings and some people hate homebrew campaigns. Again, be up front so no one gets surprised. Maybe you have a series of adventures in mind that could be set in several different settings - if it pulls in a couple of players consider using one of them. Maybe it only makes sense in your homebrew world - in that case stick to your guns and make your case. Once you have a campaign going, some of the die-hards may change their minds.
Third: Maps and Mini's or "Theatre of the Mind" - I don't find this to be a make or break for most players but it's good to know before they go and buy mini's for their character, a sidekick, an animal companion, and their summoned creatures. Heck, maybe you're going to use legos - that's cool, just let people know up front. This also impacts the playing area, and if you're not hosting you might want to get that worked out ahead of time.
Fourth: Campaign Style - Published Adventure Path? Sandbox? Modules? Megadungeon? Conversions? Different editions may cater to one style of play over another, and people may make certain assumptions, so it's best to give your players some idea of the plan here, especially with a new group. It doesn't have to be a novel:
- "I want to run a 3rd edition game using the Age of Worms adventure path set in Greyhawk" pretty much sums it up.
- "I'm going to run a homebrew sandbox using Labyrinth Lord and the Advanced Companion starting at 1st level, details to follow" works too.
- "This will be a limited campaign of 4E D&D starting at 11th level to play through Against the Giants set in Eberron" is another perfectly acceptable setup.
Again, once you have an established group you may not need to be that specific, this is assuming you have a new campaign with a new group. I didn't spill the plans for my current 4E game to the players other than "we're going all he way to 30" and that was fine for us.
Other Stuff: Starting level (not every game has to start at 1st), usage of electronic play aids at the table (I like my players to use real dice when we're sitting at the table together), character restrictions (race, class, multiclassing, etc), do you prefer characters to be ready to go for session 1 or do you want to make them together - all the little details that may not be universal to every group. Some of these may not need a declaration up front, but it's good to at least consider them as everyone comes together for the first time.
Once you get all of this nailed down and get your game going then the other stuff applies, particularly the keeping it going advice. Set a schedule, stick to the same game, etc. Some D&D-specific pitfalls:
The TPK: Sometimes they happen - I try to take it as an opportunity to assess the game as far as what we're doing and what the players want to do now. I usually ask my players if they want to continue, if they want to change something, or if they want to start a completely new campaign. This is an opportunity to better align the game with what your players want if there is a gap there. Maybe this AP is boring them, maybe this megadungeon is not what they want to do anymore - find out and see if you can fix it.
Sometimes feelings get hurt so it's important to air that out before continuing like nothing happened. Maybe there is some intra-party friction, maybe some of the players feel like you're being unfair in some way - get all that out in the open and resolve it before you pick up the dice again. I have found this to work better in person than over email if possible.
If you have some intricate plot going then a TPK can wreck the entire campaign in one session. If things are more open then it may not even slow the party down - everyone makes up another character (or pulls out their backup), meets up in some plausible fashion, and then heads back out into the wilderness/dungeon. If the plot is tied to a particular family, cult, or region then at least some of the replacement party should share some of those ties. It's another reason not to build the entire campaign around a particular character - because sometimes they die!
The Edition Change: You wouldn't think this would come up often enough to be a real problem but, well, it has for me. Here's how I have dealt with it in the past:
- Basic to AD&D: we kind of just ignored it, mixing and matching parts some of the time, playing exclusively B/X in some campaigns, exclusively AD&D in others. We took Basic characters thru Saltmarsh and AD&D characters thru the Isle of Dread so it wasn't a huge deal back then.
- AD&D to AD&D 2E: At the time our AD&D campaigns had petered out and we were playing a lot of other stuff, mainly GURPS and Hero. We took the new edition as a time to start up a brand new campaign at 1st level and it was a lot of fun. We added some new players and got on a new regular scheduled for the 2E game and kept it going for a long time with the same party.
- 2E to 3E: The 2E Greyhawk game I was running had largely run out of gas so this wasn't a conflict - I started up a brand new campaign in Greyhawk using 3E and kept it running for years. The 2E game I was playing in had reached some higher levels and our characters had settled down into one region, so for 3E we fired up the next generation, mainly playing heirs and associates of those 2E characters in the new rules, setting out from our home base to look for new adventure. It worked quite well and gave that whole campaign a fresh start.
- 3.0 to 3.5 - We ignored it. I told the group if anyone wanted to bring in a 3.5 character that was fine we would just work through it as it came up and that's exactly what we did.
- 3E to 4E: Well I mostly ignored it. We had started up a 3E Adventure Path with the intention of playing through the whole thing and no one was terribly interested in switching systems, so we just kept right on trucking with 3.5 until the group ran out of gas. Then we took some time off and I started up a 4E game with a new group (some of the same players, some new) that had nothing to do with our 3E runs.
With Next on the horizon I'd say it's going to be very difficult to switch an existing 4E character over to Next and keep anything like the same feel. I would recommend finishing out your 4E campaign and then deciding whether to switch. Also, with next still being in "test" mode it's going to be tricky to run a campaign using rules that are in pretty significant flux too. There's a point in favor of older editions: You don't have to deal with this problem. In general I don't like switching rulesets in the middle of an ongoing campaign. If we started it in 3E or 4E then I'd like to finish it in 3E or 4E, assuming it's a campaign that can be "finished". A sandbox or megadungeon could be a a little trickier but even then you might pick a level to call it "done" and let it go when the party hits that.
There's also the question of players' willingness to buy new rulebooks. For 3.5 and 4E my group was not interested in rushing out to spend more money on new books. This makes it easy. Other players have a fixation on only playing the latest and greatest - if you don't switch you may lose them and there's not much you can do to compromise there. Let them go and invite them back when you do make the switch.
What edition would I use if starting a game with a new group today? I'd probably see what my pool of players preferred and run that, with the understanding that as next starts to crystallize I would want to give it a try down the road. If everyone likes 4E do 4E. I don't know that I would promise a 1-30 climb if you're interested in what's coming Next but you could start at Paragon tier and work through that. If everyone likes Pathfinder go ahead and run it - it's not going away anytime soon. If there's no clear best choice then pick up a retro-clone and a megadungeon and try some old school operation for a few months. I'd probably call it a "limited campaign" and put a time limit on it and then plan on checking out Next when the time came.