Man I'm wanting to try my first one soon! I'm cheap though and the thought of ruining a good brisket scares me!
there's a simple way to figure it out. season it, smoke it for a few hours, wrap in aluminum foil and put on a cookie sheet with small sideboards, put in the oven at 225 with an electronic temperature probe. Let it go until the internal temperature hits 190, turn oven down to 200 and let it sit with internal temperature 193-197 for an hour to hour and a half. It's cheating but will get you a very good brisket and you can get the feel for what the meat "feels" like at the different stages. Once you figure out the "feel" (poking with finger), more time on the pit and less in the oven ... until you no longer use the oven.
I have a lady that I frequently work with that lives in NH and always wants to go eat Texas BBQ when she is here visiting. I told her the above trick to learn and she shows off to all her friends in NH with her Texas brisket and now uses only a small offset pit she found at a local to her HW store. I also taught her how to do pork ribs using similar theory. She is the rave of her friends now. It's not hard, just takes time to figure out how your pit works best and the right "feel" of the meat.