3-fingers & thumb technique

[odiolitos]

I've recently tried pulling off this one, which is supposedly used by Vic Wooten and Gary Willis, just to keep stress from my index and 2nd finger, but never quite get it right: I always mess up when changing strings and stuff.

I already know the order should be: thumb, 3rd, 2nd, index and back, but I have trouble for example muting strings or playing straight 8ths.

Any recommended exercise? Thanks a lot