Join Date: May 2003
Location: London, England
I would say dont hold the whole shape (15 and 14 on E and A) put those on as you hit them with the pick.
Then for the 12 on 3 g b do this ever so tricky rolling technique. To practice just start with say 7th fret on the g and b string, and just try rolling them as others have described. I find its not rolling literally, its more pushing the pressure around in your finger.
Try laying your finger flat on a table and applying pressure up and down it, feels kinda like a worm moving.
Learn how to apply pressure with the middle of your finger, as we all know how to do it with the tip (durh) and I found the beggining of the finger to be quite intuitive to apply pressure with.