Use a sharp knife to remove hard pieces of fat off of the brisket. On the fat cap, you want to make sure that your fat layer is about a quarter-inch thick. You don’t want it more than a half-inch thick because your seasoning and smoke won’t go through that much fat. On your meat side, you want to remove any membrane or larger pieces of fat. It is okay to remove some meat to give your brisket an overall even shape. Remove any small thin corners of meat because they will be get burnt. Here is an excellent and detailed video on how to properly trim your beef brisket.