Watch the Bending Notes online guitar lesson by Steve Vai from Alien Guitar Secrets: Passion & Warfare
Your intonation will also be very important when find yourself bending notes, which is a study unto itself. I've spent many hours just focusing on bending notes, and there's a couple things I can point out here that you may want to be aware of. When you bend a note, when bending two frets, I always recommend coming down onto the strings in a way that gives you stability and leverage, as I demonstrate in the video. A lot of students I see use their fingers to bend the note, which is squirrelly and not consistent sounding. Using your fingers makes it very hard to get to the note, but using your wrist makes it much easier. The same goes with pulling.
Intonation is so brutally important when you're bending notes, and there's a couple great exercises you can try. If you sit for an hour a day for a few weeks (or a month) and focus entirely on bending notes, you're going to get very bored. But you must push through it - remember that every time you hit the right note it's a victory. Try sitting for an hour and hitting a note, then trying to bend to it from a different string. This will help you nail your intonation when bending, practicing all over the place. Also experiment with bending one fret with every finger, with endless combinations of how you can practice. I would even goes as far as bending 3, 4, or 5 frets. And if you have a whammy bar, it can be very helpful for when you want the guitar to sing, played with a combination of good intonation, high notes, and bending.