This is a great left hand exercise that I call "killers". It reminds me of those running up and down the floor drills I used to hate in Junior High basketball. The ones where you start on the baseline and run up and touch the free throw line, then back to the baseline, then to half court etc., etc. Whew! If you do this exercise enough, it will have the same effect on your fingers as those running drills did on your legs!

Practice the first phrase, (the first 6 notes) until you get the hammer-on/pull-off configuration down. You start each phrase with a hammer-on, you don't pick at all with your right hand, and continue up the neck. It is just written out going up the neck, but you should go down the neck the same way. The next step is to go to the 5th string and do the same thing. You can go up and down each string the same way. If you do the same pattern, you are changing keys. If you change the pattern of whole steps and half steps on each string, you can keep each string in the same key. This makes it useful in your soloing as well as a great exercise.