Welcome to the family, SmokeAZ,
I would offer a couple of suggestions. What was the brisket? Choice, Select, Prime? I usually go choice or better. I also look to buy the cryovac briskets, like they sell at Costco. These have a little more fat, and that is a good thing, especially when smoking for 18 hours.
I have, in the past, injected beef broth into my briskets. This can add extra juiciness. I have also used a liquid marinade, such as Claude's Brisket Marinade, overnight. I simply place the brisket in a black garbage bag, then pour in the marinade. Place this in the fridge overnight before smoking.
When you smoke the brisket, I wouldn't trim any of the fat off before smoking.
Make sure you don't open the door, either. Just set your smoker to 225 and let 'er go.
Of course, these are merely suggestions. Feel free to take or ignore as you see fit. Either way, take good notes of what works and what does not, for future reference.
Good luck!
Darren