I have two questions on tapping-

1) What part of my finger should I tap with because I grow my fingernails out to finger pick?

2) When tapping, should I put my thumb behind the fretboard or not?
I usually use my index finger or my middle finger on my right hand (im a righty) or if i want a different type of tapping i use my pick. try both the finger and the pick see which one you like more. oh and i do keep my thumb behind the neck. a fun song to try tapping with is Oroborous or Oroboros i forgot how exactly its spelled but it's by Gojira.
1. Finger sounds better, imo. Don't use your nail - use your middle finger pad and build up a callus. Also, I've been told by several experienced fingerpickers that it's best to use your finger pads, not the nail, especially when you have full calluses.

2. It depends - if you're moving your left hand a lot, hold the guitar in a classical hold. If you aren't gonna move your hand around a lot, hold it however is comfortable.
Wow, hey I never tried putting my thumb behind the fretboard.

I learned something today.

But I know Van Halen uses his index, and Zakk Wylde and just about everyone else uses their meatier middle finger.

I usually bring my guitar in towards me and use my wrist to power the tapping. I try not to hit my nails on the string, as it will deaden its ring.
GTFO my sig
when you tap you have to through the notes away so tap and pull away from you (if that makes sense)
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