Welcome to the board, Melissa.
There are several ways of achieving tender, moist brisket and doing a search here will help you find several. Finishing in a pan of stock will might give you a lovely pot roast but not the barbecued brisket you seek.
Filling the pan with beer is a waste of beer. Flavoring the water (or replacing it with another liquid) adds nothing to the meat; flavors are added by marinating, injecting, rubbing or, later, with a sauce.
The biggest factor in Q-ing a brisket that ends up moist and tender is the brisket itself. It is harder if you're using 'Select' grade meat, especially if the meat is near the bottom of the grade--there's just not a lot of intra-muscular fat and connective tissue to work with.
Usually, if a brisket cooks tender but dry, it is a bit overcooked, it didn't have enough IM fat to begin with, or a bit of both. Foiling, with or without liquid at, during, or post-plateau (depending on what you've got) , can help a lower-grade packer or a lean flat maintain moisture. Some people feel that foiling with liquid can make the meat pot roast-y. Personally, I think that's more of a potential if liquid is used with an already well-fatted cut. You can still turn out a good brisket that starts out on the lean side without foil; the 'done' window is a bit narrower though.
