#1
I have massive trouble getting a vibrato during a bend. How do you do it and what are some tips?
#2
make sure youre using as many fingers as possible while bending, i think the easiest is with the ring finger, and have the middle and index for support. start slow, and try to do just a small amount of vibrato and work up to what you want. its def not an easy technique, but its also not impossible, and its worth the effort to get good at it.
Jackson RR Professional, early 90's japanese model, with EMG's

Digitech GNX3000

Crate GX 212
#3
Now that my finger are stronger, it is easier for me to apply a vibrato to a bend. Keep practicing bends, your fingers will get stronger (have a good warm up before intensively practicing bends with vibrato). The 2nd and 3rd fingers are easier to bend with. Work on half step bend/vibrato first and then move on to greater bend/vibrato.

Hope it helps
#4
Aww, man. I remember how difficult I found this when I first tried it. It's pretty much the only vibrato technique I remember actively practising. I don't have any real advice other than keep at it! It really is as simple as vibrato but on a bent string, it just takes a long time to master.