To keep mice and other rodents out of your home, here's what you should do:
Get rid of any mice you see. If you see a mouse, don’t wait to deal with it. If you notice any signs of mice, like droppings, a foul smell, or chewed-up materials, assume that you've got a mouse hiding somewhere. If there's a mouse in your house, you have essentially two options: baiting or trapping. No matter which type of device you use, place them in areas you've observed the rodents or their signs.
Seal holes and cracks. Check doors, windows, and vents all over your home, and seal even the slightest gap that you find. Mice can squeeze through almost unimaginably small openings.
Seal food sources. Keep your food in sealed containers, and keep your pantry tidy. That includes pet food, too; don't leave bowls of pet food lying around.
Keep things clean. It goes without saying that rodents are attracted to easy food sources. But it goes further: piles of trash or debris—inside or outside—are prime hiding locations for vermin. Keep your whole property tidy to make it harder for mice to sneak around.
Watch your greenery. Shrubs and other plants growing right against your home make it easy for rodents to hide while they're seeking an entrance to the house. Keep dense plants at least a few feet away from the house. Similarly, keep tall trees pruned back so rodents can't use them to hop onto the roof.