New to GM
So, I've had a lot of ideas for games like only war and dark heresy but I also want to do a deathwatch game. This is my first time being the gm and I know one player is very into role play while the other wants to be the biggest and baddest guy he can be. The general game idea is that there is a traitor(s) in the Deathwatch and the pcs are thought to be them. This will turn into a quest to set things right while fleeing from their fellow marines, and battling the followers of tzeench. So aside from a general, I want this plot and startup, I don't know much.
I'm open to any advice on running the game, as well as satisfying both types of players.