This is Bent's old brisket recipe that many find to be a good basic starter.
Get as big a brisket as you can. I try and get 14, 15, 16 lbers, they just seem to cook the best.
Trim the real thick fat on the cap and the side, but leave the rest, I mean all of it. What does not render in cooking, you just shave off before carving.
Inject beef broth, beef stock or bullion, mix in a good savory rub. You should use about 24 oz of liquid and about 4 Tbs of rub. Don't be afraid to throw in finely chopped garlic and black pepper if you like that taste profile, stir it up and let it set about 30 minutes, then strain through cheese cloth (phosphates are our friend if you have any). Inject it all over. If ya don't have an injector just forget that step.
Pellet choice -- ahh that's the fun, and your guess is ad good as mine. I like Hickory, Maple and Pecan if ya have it.
Cook time -- I will usually figure about 15 hours for that size brisket, just a bench mark. I will usually cook it at 200° for 3 hours then turn to 240° at about the 11-12 hour mark it should be between 155-175° internal temp. I like to put in full size aluminum pan, add 1/2 cup of stock with 2 Tbs more rub. If you have a remote probe, stick it in, tightly foil and put back on pit at 240°. It should take about 2-3 more hours, set gage to 200°, when it goes off start poking and pull it when you like the feel (for family and friends should be like skewer in soft butter). It should be fat side down all this time, or that is the way I do it. Let it rest an hour in its juice on the counter top.
I think you will enjoy.