A couple methods:

Use rubbing alcohol or peroxide to smother the tick - the idea is that it
won't be able to breath and will let go.  At the same time you are trying to
drown it (the tick) by pouring the solution over it you should be holding
the body w/tweezers and GENTLY pulling so as soon as it lets go you'll have
it.  4 hands works better than two w/this.

We also used to use a hot match - light it, blow it out and apply it
immediately to the tick body while pulling w/the tweezers -- theory is tick
says 'ouch' and lets go.  Again, easier done w/two people.

Most important is to NOT leave the head of the little nasty in the kitty
that's how you get infections.  Best to try and get it out than to leave it.
Or, call your vet and see if you can move the app't up and they can
teach/show you how to remove it.

Good luck,
LeeAnne