Burn 'em, chew 'em and maybe slice 'em. Stick in the frayed wires straight into the reciever... that should work, right?
Personally, I like fuel tubing instead of zip-ties, but if you know what you're doing...
The best thing to do is unscrew the bottom cover of the servo, de-solder the leads, cut them to length and re-solder them back in place. No mess, no fuss.
... ^that's the best thing to do with them pesky wires.