Cook Temperature -- if using a kamado grill target a temperature of 225 degrees Farenheit
Rub - Keep it simple, salt & pepper. If using a pellet cooker which doesn't impart as much smoke on the meat you can supplement with more spices
Not allowing enough time before you have to serve it. Each brisket is different. Add 2.5 hours to your cook time to be safe
Not allowing enough time to rest. This helps with moisture and tenderness. Minimum is 1 hours, strive for at least 2 hours of rest
If cook is <8 hours can put directly in the cooler, stay hot and slowly come down in temp
If cook is 8-12 hours, let brisket down to 180 degrees, then to cooler
If cook is 12+ hours, let brisket come down to 165 degrees, then to cooler
Don't change too much
Don't change everything from last cook you tried (temperature, rub, injection, wood, water pan). You won't know which affected the cook (good/bad) vs. the last time
Five key things to look for before wrapping the meat
Color --> proxy for how much smoke flavor. Darker yields more smoke flavor
Bark build is a necessary pre-condition
Evaporation --> want the brisket to sweat out water, shrink about 40%. If don't allow to sweat out enough, will fill wrap with lots of moisture. Create soup that washes off the bark
Fat render --> fat on top turns yellow, when you poke it there is no resistance
Temperature --> not the end all be all, just one component. Typically check the other 4 things first. As a fail safe, generally wrap around 175-185 degrees, but could be as low as 160 and as high as 195.
When spraying brisket, don't spray the fat. The point is to protect the meat. You want fat to render, so spraying is counter-productive.
Over/under smoking. Know your cooker
Avoid wild temperature swings
Getting low quality meat
Don't have to get Wagyu. At a minimum get "Choice," you can't make good brisket with Select. If can get Prime, get Prime
Wrapping improperly
Whatever using (foil or butcher paper) do it well. Make it nice and tight.
Improperly trimming the brisket
Bad idea to try and trim off all the fat, can cause the meat to come out dry
Don't be reluctant to trim off parts of the brisket. Don't leave a piece on the brisket that will just dry up and burn. When trimming the flat, be merciless.