Brisket comes in a few ways. First, is the whole, entire brisket, this is called a packer. It consists of two separate pieces of meat, the point or deckle, and the flat. The flat has less fat than the point does. A whole brisket can weigh from 12-18 pounds and can take upwards of 24 hours to smoke until it is tender.
I would suggest you start with a flat or point, around 7-10 pounds.
Starting 1 day prior to cooking.
Trim away fat until you have around 1/4". Make an injection of 1/2 beef broth and 1/2 apple juice and inject all over the meat. You will see it swell. Then make a slather of 1/2 dijon mustard and 1/2 worcestershire sauce, and paint on coating on it. Put it in a large ZipLock and place in the fridge for several hours. Take it out and rub it with your favorite rub, a good one to try is Billy Bones' Beef Master, or you can make your own. Return it to the ZipLock and fridge until tomorrow.
1 Hour prior to cooking, remove from the fridge.
Get your smoker ready, and have your probe thermometer on hand as well. You may put another coating of rub on it if you wish at this point.
When your smoker reaches 225-250, Get two large aluminum catering pans and set them inside each other to make a very sturdy one. Place a rack over it, set your probe into the meat, put it on the rack. Add beef broth and stick of butter to the pan. This will be a base for the dripping to catch in. Place it in the smoker. Equal parts beef broth and apple juice into a spray bottle to keep the meat moist every few hours. When the temp hit 165 on the probe, take it out and double wrap in heavy duty foil and place back in the smoker. When it hits 190, it is ready for slicing, let it go til 195 if you want to pull it. Take it out and wrap it in a towel and place in a dry cooler for an hour or so to let it rest. Serve with the drippings, your favorite sauce and enjoy. It will look like a meteorite, don't worry, it is supposed to look this way. Remember to slice across the grain for tender slices.
It may take some time to cook, but figure around 45 minutes per pound. And the temp might climb quickly, then stop alltogether for a few hours, then it will resume. This is normal, don't sweat it.
Burnt ends are made from the point. After the brisket is cooked, pieces are cut into 1" chunks, tossed with drippings and sauce, set in a pan, and placed back into the smoker for a few more hours.