Cats collar problem!?

My cat really needs a collar, to frighten animals away so she doesn't kill them. We get fed up with dead animals being brought into our yard! Although it is very natural we still don't like seeing the left overs of what had been caught. Also we would like to put a collar on her to stop other people thinking she is a stray. But the question is, is that she will not wear one she will refuse completely. Every time I get the collar out, she freaks and backs away, I aren't going to keep trying and chasing her around otherwise I might make her stressed. How will I put one on her, when we first got her she wore collars but both got lost. How am I going to put this one on her?