Tips for buying brisket
The easiest way to buy a piece of brisket is at a meat counter where they have it pre-trimmed or can trim it for you. Try to buy a piece of fairly even thickness.
There are two cuts - the first cut and second cut. The first cut will be very lean. Most stores carry this cut. The second cut or deckle has much more fat and marbling in it.
If you buy a whole brisket, it will have the deckle and the first cut - the deckle will be on top.
If you buy whole brisket, you will pay less per pound but you will need to trim it. You'll have to cut off some pieces that are similar in thickness so it cooks evenly under pressure. Just count on an extra 20 minutes or so to prepare the meat.