Although made popular recently by Eddie VanHalen, guitar tapping or right hand 'legatos' is a technique players have been executing for years. Country players know the benefit of laying down a nice subtle lead and just putting in those quick hammers with clear guitar tapping. And while it's not the easiest thing, guitar finger tapping techniques are really nothing much more then fast hammer on and a pull offs. Whether you use your middle finger or your first, most times you can hold the pick as usual to execute your guitar tapping and get the speed and positioning essential to good guitar tapping techniques. But like anything else, guitar tapping takes practice and patience.
Since this is a highly specialized, yet popular way of playing we hear a lot of player's guitar tapping these days...and just as many tapping badly. Especially when a guitar is cranked through distortion, a whole host of extra noises will come out if the player's guitar finger tapping techniques aren't the cleanest. An important trick to 'clean-up' when you are cranked through that Marshall Stack and you're in "overdrive", is to rest the back of your right hand on the lower strings for muting; what you want to avoid is these string making a lot of extra noise while you get that guitar tapping in one steady movement. Of course, if you're a rock player you are most likely already dreaming of the all-too flashy 'cross-handed tapping' but this is so impractical it only ever works when playing live (and even then it is a hard to get those guitar tapping progressions cooking in this way!) Admittedly though, this particular type of guitar tapping, above all other types of guitar finger tapping techniques, creates a truly distinct tone.
There are hundreds of videos and books that show guitar tapping tips, but as it is with everything else, you can't even begin to understand how guitar tapping works until you get up and do it yourself. Although modern listeners have been conditioned to want speed like Eddie V., it is more important to get the strong and clear sound of each note then to sacrifice technique for potential sloppiness. Guitar finger tapping techniques are only good if you can do them; nothing sounds worse then reaching for a flashy technique and not being able to pull it off. As with everything else you learn on guitar, if you mater a technique on acoustic then you can feel all that more confident trying it on electric.
Playing a difficult and flashy exercise, such as guitar tapping or lightening fast arpeggios, sometimes seem to be easier on an electric; you get-off on the sound you are creating, the noise, but don't catch nuisances or mistakes. Try tapping on an acoustic guitar (or you want a big challenge-try guitar tapping on an acoustic bass!) Guitar finger tapping is hard on an acoustic; cross-handed guitar tapping is almost impossible (it takes a ton of strength and precision), but master guitar tapping on an acoustic and you'll find you are that much more prepared for what you might do on your electric.