Open string riffs are common in all styles of rock music. This particular riff builds up strong technique without being overly challenging. By the time you have this exercise mastered, your right and left hands will be in sync like never before.
To begin, take notice of the pick pattern. For each set of 16th notes (4 notes per beat which are counted as 1 + e + & + a), you pick down on the first note (the “1” count), pull off to an open string for the second note (the “e”), and then pick up on the third note (the “&” of the beat). You then pull off again to the open string for the fourth note (the “a” before the second set of four notes begin). This could easily be played with hammer-on and pull-offs, but by approaching it this way, you will develop strong coordination between your right and left hands.
Once you are comfortable with this exercise, practice moving your left hand up and down the fretboard and experiment with different notes and strings. Not only will you have a great warm up routine for your hands, but this may also spark some new ideas for your next song!