I like this thread done by Bigabyte, it is outstanding.
I do hot and fast briskets now, find them easier to do.
Inject the night before if you are going to inject. Trim excess fat, at least to no more than 1/4". I try to trim to 1/8". Rub with whatever rub I am going to use. Let sit while lighting and stabilizing smoker. I often turn a fan on low over the meat during this time.
Run smoker or kettle at 275F to 300F indirect heat, make sure light blue is flowing, put on brisket, fat cap down, and let run until internal hits 195F for a full packer, 190F for a flat. I do not foil, nothing wrong with foiling, I just don't. I probe at 195F (190F for flat) and do so at 5 degree intervals until the meat is tender to probe, almost no resistance.
Actually, I probe at 165F, I can't help doing it, but, as Divemaster says, this is not really necessary as the meat will not be done at that time. It is a bad habit.