I've never brined one, but I usually keep mine VERY moist by two moves:
1- inject with plain ol beef broth - wont make it taste like anything other than good old beef. You'll never know its there other than a juicy bite!
2 - place in poll pan with foil wrapped over the top once bark has set (160-ish deg).
That'll pretty much guarantee a moist brisket. Good luck!