I learned it first by playing a one octave-scale and bending only the last note (ni to sa'). Also Murchana's with the last note bend were helpful. Later, gats were taught that had one note meends. So slowly building it up. I've been studying now for 2 1/2 years and right now were tackling 3 and 4 note meends.
I also got to add that I'm studying surbahar now with Pandit Ashok Pathak for only three weeks and his way of playing meends is stunning. Really subtle around the note, so it's back to the drawingboard! He makes me listen in a totally different way to play meend. I'm sure that every gharana has a different approach to meend.
Pardon me if I state something wrong� I�m still learning.
I don�t have a teacher (I wish there was one nearby) but I�ll add my approach from the perspective of self teaching and I definitely won�t state that it is correct. I decided to immediately jump into learning two note meends while also learning other techniques. So far this is working for me.
For anyone who may be curious, this is how I�m practicing meends.
As a guitar player I already understood the basic idea of bending notes:the meend. So I based my practice from a guitar players perspective. Here�s what I�ve been doing and it sure seems to be working.
I start by tuning all 18 strings with a chromatic tuner. I then play a high Sa this becomes my reference note. Then I move down one fret and meend (without picking) to the Sa note. Then I pick that �bended� note to see if I have actually hit the correct pitch. If I haven�t hit it, I start over until I do.
Then I pick the (un-bended) Ni note (as my reference pitch) then move down one fret and repeat the same process with each descending fret. When I reach the lower Sa note, I repeat the whole process in reverse.
What is starting to happen is that my fingers are getting the feel for the correct amount of meend on each fret.