The basic blues formula is fairly simple — but to really get a good handle on it, you've got to play in a live setting with other musicians. And what better way to hone your chops than jamming at the legendary El Chapultepec with guitarist David Booker, a Brit transplant who's been in Denver since the '80s and has performed with Bo Diddley, Solomon Burke and Rufus Thomas? The jam, which Booker started in October 2009, gets a steady stream of regulars that includes a fair amount of guitar and horn players.