Get some wood chunks, soak them in water overnight. Sear the brisket over the propane grill. Turn off the burners on one side of the grill. Put the Brisket on that side. Put the wood chunks over the open flame side down in close to the flame. Close cover. Adjust the temperature to 210-225 if you can get that low, otherwise, as low as you can go. The goal is to build a heavy, dense smoke for a shorter period of time. After a couple of hours see if the brisket has formed a "bark" on the outside. Once it has, bring it inside and put in a 210 degree oven. If you like a moister meat, wrap in foil, if you like dryer meat with a crunchy bark just put in a pan. Give it a good 6-8 hours unless foil wrapped, then you can go up to 12. Recommend serving BBQ sauce on the side, not over it.
The rub before you start cooking is very important. the recommendations by all the Brothers are excellent.
Also, if you wrap it in foil, you can take off a fair amount of excess fat off the fat cap before you cook it. If you are not going to wrap it, leave a bit more of the fat cap on to provide moisture for the meat. And always have the side with the fat cap on top so the fat can trickle down and baste the meat.
I have to add how I came up with this; My wife and I were visiting her Father's widow quite a few years ago outside Gulf Port Mississippi and as it was her Step Mother's birthday, my wife invited a bunch of her Dad's Widow's friends from her Southern Baptist Church over for a birthday party. And of course she tells me I need to Barbecue for them-ALL of them. She had a small three burner propane grill to do it on. So quick I went to Sam's, got a big brisket, got it in brine the day before, took it out and rubbed it down the night before. Got up at 2 am, as the party was at 2 pm the next day. Cooked it like the above instructions, and sure enough, most the church of good ole Southern Boys and their spouses came the next day. Really fine, nice people, but I was nervous at carrying coals to New Castle. That is, these people KNEW Barbecue! And I hadn't had a chance to taste it. Well, after we ate, one guy went out in the yard and was looking around so I asked him what for? His response is he wanted to see the brand of smoker I used so he could get one. When the Minister left, he shook my hand and said it was a miracle that a Yankee like me could make such good barbecue. SO I guess it worked pretty good. However, they did not leave me even one piece to left over.