Trim as much fat off of the brisket as you can. If you use the entire brisket, it will have a layer of fat between the flat & the smaller piece. Purists will want to kill me, but I seperate the two & trim most of the fat from both. Coat both sides with your favorite dry rub. I use Emeril's Cajun seasoning. I make my own. You can get the recipe off of FoodTV. The difference is that I ad summer savory to the mix. It adds a great fresh flavor.
Place the brisket on a BBQ with the smaller piece on top of the flat at very low heat-200 degrees for 10-12 hours. YES, it takes that long to do it right.
Once done, slice across the grain, put into a slow cooker (to keep warm) with your favorite BBQ sauce. Serve as slices on the plate or in a bun with cole slaw on top of the meat. It doesn't get much better than that.
One word of caution...put a large fat catcher tray under the meat. Even with the best trimming there is enough fat that it will drip & cause a mess & possibly a fire.
I use a natural gas grill, so long cooking doesn't take much effort.
One more trick, soak wood chips (hickory, mesquite or whatever you like) in water & put in BBQ with the meat for even better flavor.