I haven't led any guilds here (too smart for that now

), but I was raidleader and the most vocal officer (we didn't have a guild leader) of a high-end raiding guild in EQ for years. I've also managed (technical) people for 7 years IRL.
Outside of the (excellent) advice already given here, I would just add:
(1) Communicate often to the guild, even if it's "known" stuff
Particularly in times of stress (uncertainty, unhappiness), people need to know that someone is at the helm and is thinking ahead -- even if there's no new news to add.
(2) Use your officers
Ok I lied, this was said before, but needs to be said again. The worst way to run a guild is to refuse to delegate. Sounds like you're starting with a good set, so you're in a very good position there.
(3) Manage burnout
This goes along with #2. The best managers (IRL) can leave their team, suddenly, for a few weeks, and come back and everything was just working. This also means they *can* leave and take a break.
Burnout is the worst danger you face. Build up sufficient delegation and automation into the guild so if you take breaks it can keep running -- and then take those breaks.
(4) Your job is to make the tough decisions - make them
Firing someone is always tough, but if you don't, the good people leave. Remember that no decision (and inaction) is a decision (and an action) -- there's no escape, so think about it, make what you feel is the best call, and stick by it (unless it's really clear you're wrong, then don't be afraid to say 'I'm wrong' publically and step back from it.)