With this first riff, we're going to be repeating it in a few different ways, mixing around the picking execution as well as the octaves. We'll also be using sixteenth notes exclusively.
To start, check out the first 4 measures. Notice how the notes are played primarily using legato? There will only be a few downstrokes needed when you start the note sequences on each string. Also, observe how every other 2 measures, you'll be switching from a higher to a lower octave. The actual shape of the riff will remain the same, even though you'll be shifting to different strings.
Then, beginning on the 5th measure, you'll begin alternate picking each note. I actually like the sound of legato better for this particular riff, but I figured we might as well mix in some different techniques so we can give ourselves a good workout.
On to exercise 2!