cutting the tails off?
not a bad idea... i find tails really horrible to use.
but i suppose they do look pretty.
try this instead: if you're tangling up, it might mean you're not moving your hands in sync enough. A steady rhythm might help, are you listening to music when you practice?
you could also try doing the move holding both ends of a shortish stick (or wooden spoon or whatever) in your hands to get used to moving them at the same speed, and keeping the distance between them constant - which should help
oh and i'd suggest starting with your hands in front of you, sway the poi to one side, then as they swing back swoosh them up and behind your head.
if all goes well then they won't tangle and/or hit you in the face
ooh and its easier to learn to do it both ways (clockwise and anti-clockwise) than to learn one way and much later re-learn how to do it the other way.
edit - doh. late help. ah never mind...