You need to determine what kind of players you are playing with. Some enjoy story lines, pursue growing their characters, most just like to kill stuff. Its' best to play with like-minded players.
Always have game chat before the game starts. The best thing to do is chat about what you would like to see from the game with each other while the GM is setting up. I'm sure the GM will be eve-dropping, and some of it may be incorporated into the campaign somehow. It's just always good to get everyone sykedpsyched about playing before you play.
Take Breaks! about every 30 minutes of storyline, or after a great battle, everyone should take 5 or 10 minutes break. Step aside and reflect/discuss what just happen, what was fun about it, etc...