I am not an expert at smoking brisket, yet - and everything posted already is great advice, I have been following it for a couple of months. I have done a half dozen or so, and I think the most important hint especially for beginners like ourselves, is to try and find the best cut possible. My best briskets have been choice (grade) packers (I have never just cooked a flat). If you have a selection, go through them and look for the marbling. There was a post on this site a week or so ago on folding the brisket. I read on another site when I tried my first brisket that you want to be able fold the two ends in half and have them touch. Anyway, for me so far I get better results with Choice. I want to try a Kobe brisket one day, but I have problems enough finding a choice packer.
Also I think Kevin hit the head on the nail when he said:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">If the brisket has a good amount of internal fat/connective tissue foiling is not necessary; if it doesn't it can be helpful. </div></BLOCKQUOTE>