You may get a couple of opinions on this and that is fine. Here is my way. Trim the excess fat leaving maybe 1/4 inch save trimmings. Set rack on a baking sheet. Set brisket fat side down (helps insulate from the heat). Season both sides with you favorite (we like salt pepper garlic and onion powder, brown sugar). Place fat trimmings on the lean side. Into smoker (still fat side down) middle of smoker. 225 degrees. If programmable, set the IT for 195-200. 4 to 6 oz wood (we use hickory). Turn on and walk away.
For a mid day meal, I start between 11 and 12 midnight. I check around 7 or 8 in the morning. You will get a stall around 170 degrees and it will look like the temp will never rise. It will, very slowly. When your meat has hit the IT you want, remove, double wrap in heavy foil, wrap in heave towel and place in cooler till serving time. Enjoy!
