Unfortunately it is that time of year when they are more likely to come inside. We use both traps and baits as this works best if you have a lot of them, otherwise you are emptying and setting traps all the time. Get some Racumin sachets as they wont make a mess like pellet poison and you can drop one behind cupboards and fridges etc away from little ones and pets. I've been doing a fair bit of cleaning today and found that they had actually started eating the hem of a dress stored in a place that I thought was mouse-proof!

Steel wool is good, but dont get the stuff that is really fine, because they can still chew through it, you need to get the stuff that is really shiney and like a tightly coiled spring, you will find it in the supermarket where all the dishcloths are. They can't eat through that one. If they are getting through vents, get your DH to cover it with some mesh and if there are gaps in the skirting boards, just get some 'no more gaps' and fill them in. Mice only need an 8mm gap to fit through and get inside.

ETA - Peppermint oil is supposed to deter them, but I can sprinkle the oil around a mouse trap and still catch a mouse in it or vacuum poo from where I have sprinkled it so I have come to the conclusion it doesn't work and just makes your house smell like the mother of all Minties LOL