I want to learn tapping on acoustic guitar; its basics, various techniques and so on. How should I start with it? Reference of some video lessons would be a great help.
You might want to start with tap harmonics. It's quite easy and sound really great on acoustic. Check out this video lesson: http://www.youtube.com/watch?v=FhOzgDwMHQg (skip ahead to about 5:30).
Go check out some artists like Andy McKee and his song Drifting. It's a lot easier than it looks when you're trying to learn it because it kind of repeats the same thing for the beginning but with little changes. One thing, though, is that the guitar is tuned to DADGAD.