Watch the Tapping Basics online guitar lesson by Jennifer Batten from Rock Sauce For Lead Guitar
The easiest way to get started with two hand tapping is to learn two basic rules. One is for minor pentatonics and arpeggios and the other is for major. The minor rule is that you can copy what your left hand is doing 7 frets higher. For major, it's only 5 frets higher. The notes from an A minor pentatonic in your left hand and an E minor pentatonic in your right hand all fit in the key of A minor. Likewise, if you play for instance an A major 7th arpeggio in your left hand and a D major 7th arpeggio in your right hand, all the notes will fit in the key of A major. When you analyze the notes you've added in your right hand, you're just adding extensions to the A major 7th argeggio. In this case, you've added the 4th and 6th (same notes as the 11th and 13th).