by three finger triplets do you mean playing with your three fingers to pick the strings?
if this is the case, get a metronone. start off simply by hitting the notes of any speedy tune you want to learn but at a slower pace on the metronome than the song is. the more to learn to keep control of your fingers the more consistent your playing will be and your three finger playing will improve.
or for a silly but fun way, watch a clock with the seconds finger on and play as many even beats in a second as you can
