One thing I found with mice that is fast and fairly easy. I set the mouse on my knee, holding on by the tail. I use my finger to flick it really hard right on top of the head, you know, like you flick a bug off of you. This stuns it. Once it is stunned grab it just behind the ears with your other hand and pull HARD. There will be a faint pop when the spine dislocates, and you are ready to feed.
Sometimes with larger mice, they will kick a little when you do this. Their spines are thicker and harder to dislocate. But if you do it a few times, you can get a feel for it and should rarely have a problem.
Gale