For the most part, I use a "B.B. King style" Vibrato: My thumb actually comes OFF the back of the neck, accompanied with a tight, focused shake.
Other times, like when I bend with my pinky, I will sometimes use my WHOLE ARM, or I'll pivot/vibrate from the knuckles & tendons in just my FINGERS.
To practice, I always try it slow and VERY EXAGGERATED in order to "program" the motion into my brain. I will simply bend the note to a desired pitch, release and then bend again to MATCH the pitch, repeating this over and over.
Don't worry about posting in the wrong Thread, Pebber is able move these, if necessary!