I like to inject the brisket the night before some do others don't. Also trim up the fat on the brisket unless you like bubblegum meat. Trim off as much as you can between the flat and the point. Also trim back the fat side. Rub it down with some plow boys bovine bold throw it on. I like to flip the brisket after a few hours and cook on both sides. I also pull it off with an hour or two to go and drop it in some foil then pour marinade in and completely cover it. Let it cook in the foil for an hour. Pull it out and cut off the point. Cover the flat back up tightly in the foil and let it cool for a while. Take your rub and cover the point of the brisket and throw it back on the grill. Then after another hour pull the point off and cube it up. Enjoy the burnt ends and brisket. Let the flat cool for 20 min so that it locks the moisture in.
I typically use beef broth and butter to inject the night before. It's been a while since I cooked a full brisket, it's a lot of work. Good luck and enjoy