Let's start at the beginning. Are you being launched properly into the mission? That's the first step, and some newer players have problems with that.
If you are indeed launched onto the runway at the onset, a good bet is to follow the herd on takeoff and wait for instructions. Contrary to what Lusche said, I've found that a lot of the larger bish mishuns at least are using range channel now rather than assigning a specific channel. This may just be the bish. If no instructions are sent over range, ask on range what the mission channel is.
Look around you. Are there less than about 5 others in the mission? Are they flying inexplicable plane types, such as bombers from a base that is capped, escorted by Spit I's? A good mission will have purpose in the planeset, clear voice communication from the leader within 10 seconds of launching, and decent numbers. A bad mission will have plane types oddly thrown together, small numbers, and no leadership. If you find yourself in a bad mission, you may find it best to point your nose to the nearest tree and go afk for a few.