TRIMMING AND PREPARATION
I trim most of the fat off the brisket. I leave about 1/8 - 1/4. I don't go into the crevices (between point and flat) very deeply at all. I will try and get most of the membrane type fat off where possible to allow for a better tasting texture, rendering, and seasoning (rub, marinade, glaze) penetration and build-up). This is not a point to get to anal about. Just leave a bit of fat on to self-baste, but not enough to bother you while slicing and eating. After it is cooked it all taste crusty and great! You might take a LOT of fat off your brisket. Maybe 1/4 of its entire weight. Oh well. That is the way they come.
This process can take a bit of time and a lot of fat will come off, but it is worth it.
COOKING IN A SMOKER.
I always cook a whole packer cut brisket if possible. I smoke for 1.25 hours per pound. I rotate and baste the meat ever hour and check wood chip supply and water supply. After 6-8 hours I then stop the smoke and wrap the brisket well in heavy duty foil. I cook for an additional 4-8 hours depending on the size. I cook my briskets between 225-245 1.25 hours per pound. I will start basting about half-way through the process and about every 60-90 minutes from that point on. After the last 4-8 hours of cooking in the wrapped foil I take it out and wrap it in towels and place it in a cooler for 7-8 hours. At that point I take it out and remove the foil and the brisket is very hot and ready to eat or prepare for refrigeration if needed. The last part (with the cooler and towels) really softens the meat further.
TRIMMING AND SLICING
When you lay your brisket out to trim or slice for the first time simply push your finger into the middle the brisket a slight distance. You will immediately detect which way the grain is going. Then cut it opposite of that. I then typically separate the flat from the point because their grains do run different directions and this gives me a chance to remove the fat in between.