Re: Any tips for a new GM?
Firstly, I would say that being the GM does not guarantee an active game, though it can help. Players post when they are available and when they can think of something to say - regardless of who's 'in charge'.
The only advantage to being the GM is that you can scene-change to move the action forward, but if you do that too often, players lose track and the game falls apart.
Note that EVERYTHING leads toward the game falling apart - that's the natural state, and only extreme effort will prevent a game from gravitating toward its natural state.
As Asraile said, a GMPC within the party is a good idea, it can be a useful tool for making suggestions when the players haven't picked up on that utterly obvious clue you left them, but do not, under any circumstances, make your GMPC the 'leader' or even a 'respected member' of the team, otherwise the players will do nothing, always looking to the 'leader' to make decisions, and you'll end up with effectively a solo game and it'll fall apart.
Players do not pick up obvious clues. They do not pick up very obvious clues. They may occasionally pick up utterly obvious clues, but often the only clues they will recognize are the ones you beat them over the head with. If players don't pick up clues, the game stagnates and falls apart.
Quite often, players have a very blinkered view of the game. All that matters to them is what their own character is doing or saying. You can find that PC 1 will state his intention to sneak past the orcs, PC 2 will, three hours later, state his intention to challenge the orcs to combat, and two days later PC 3 will log in and state his intention to cast an illusion that the PCs are a party of uruks. None of them will have any regard for the others' posts, none of them will make any attempt to negotiate an agreed tactic, either IC or OOC, and it's your job to try to sort out what's actually happening... before the game falls apart.
Good luck with your GMing. :)