Tom covered everything in his posts, but I wanted to offer some encouragement. I bought two large(17.55 & 16.85) briskets at Wal-Mart Thursday night. Brisket is the only thing I'll buy there because it seems to be the only thing they sell that dosen't have water added and they've been real consistant in price at $1.69/lb for the past year or so, while Costco and BJ's are usually closer to $3.69/lb. I've never been able to cook the "solution added" stuff to my satisfaction. It always seems to come out dry and stringy, and shrunken. Just give me a good fat cap and I'm happy.
I don't trim any fat off until after cooking. I want to give the fat every opportunity to melt and flavor the meat. I season with nothing other than garlic salt and coarse black pepper. I'm using a Smokette so I actually have to fold these over on themselves, and can cook only one at a time because I don't want to use the bottom rack. I start at 200* for the night, then bump it up to 225* the next morning, looking for 195* internal. The 16.85# brisket went in Thursday night at 9:00pm, was bumped up to 225* at about 10am Friday, and hit 195* internal at about 3:00pm. I didn't open the smoker EVER during the cook, and rather than pulling the brisket out to put in a cooler, I just turned the smoker temp down to 160* and let it rest until about 7:30 when it was time to eat. I used about 8oz of hickory, but sometimes I mix hickory and oak. I don't really care for mesquite having been raised on hickory, but to each his own.
I've done maybe 100 briskets in the smokette this way and have never had a bad experience yet. The only change I ever make is starting out at 225* when I need to finish faster. With these large briskets I don't have to worry about them getting done before I want to get up in the morning. Usually 2 10# pork butts started at 9:00pm at 225* will wake me up between 6-7:00am at 190*, and I like my Saturdays to start a little later so I started using a lower initial temp for everything with a long cook time.
I just try to keep everything really simple and don't open the door unless I get a crazy temp reading from a bad probe placement. So far this method has worked out well. Hope this helps some.