Watch the Add Open String Hammer Fills online guitar lesson by Vicki Genfan from Acoustic Rhythm Guitar Cookbook
First thing is to make sure you've got the capo on correctly on the 2nd fret. Make sure you place the capo in such a way that it leaves you some room to place your finger on the 6th string in the 2nd fret. Make sure the notes aren't buzzing. D'Addario makes this capo and calls it DADGAD capo, Kyser calls theirs "Short Cut". There are probably others.
Let's start with the riff that repeats throughout the study. Make sure you've got the right combination of hammer-ons and slides. For the F#m11, you want to make sure you have room in the 2nd fret for your finger to play the 6th string. And finally, on the last chord – remember you don't have to move your finger at all once you've played the last note of the riff. Enjoy!