Well, I can't say what the "best" way is. What I've always done is put the multi-trap into a bucket of water, fully submerged. Sometimes I think snap traps are the best because the mouse gets it's neck or back broken, but they only catch one at a time. If you've just trapped 15 mice... well, a...
Traps work, I can recommend the multi-use traps that can trap and hold many mice. You have to check them every day, and kill the trapees, but unless you have some sort of eradication program in place just you being there feeding the chickens will help mice to explode in population. I always...