speed tapping

Mostly joe execute his fast tapping by using his guitar pick. He achieve that effect by tapping the string withs the edge of the pick rather than using his right fingers. You need to practice it until it sounds perfect because sloppy playing will not result it nice tapping sounds.

the only thing you really can do is practise make sure to stretch also Stretch 1 go up and down from E to e -1-3-2-4-4-2-3-1

One of the golden rule to play fast is to play slow. This means play slowly first by building memory in your fingers. By playing slow you also able to notice your mistakes that hinder you from playing fast. When you have get used to the motion, gradually increase your speed, until you reach your desire speed. Many techniques like tapping, sweep picking, tremolo picking can be mastered by playing slow. A metronome can help a lot. Hope my advice is useful for you :)