Hi Tony! Good to have another T on here!
I suggest brining for a flat, as they're hard to keep moist and nothing makes meat hold moisture more than brining. I, personally, don't inject if I brine, but Walt has a killer brine/inject process. I also never foil anything, brisket included. Use a water pan, on the floor of the smoker next to the smoke box, put the meat as high as possible, and watch the internal temp. Start checking the feel at around 190. You're looking for "squishy" (I love this description, by Pork Belly). It should be soft and flexible, and tender to the touch, like you could stick a stiff finger through it, with a nice moist bark.
Snoop around the beef section, and do a search on brisket. No need to reinvent the wheel completely, as there are hundreds of posts on this subject.