Start with entry gaps, food storage and sheltered corners before colder nights arrive.
Inspect under sinks and around service entries. Repair small gaps with suitable metal filling and compatible sealant.
Replace worn door seals. Check the door between your garage and house too.
Use sturdy containers with tight lids. Clear crumbs and put pet food away after feeding.
Keep wood piles away from walls. Clear spilled birdseed and trim shrubs so you can inspect the foundation.
Look for loosened filling, fresh gnawing and new droppings. Continuing activity may mean another route remains.
Mice already inside need removal too. Follow the checks for kitchens, garages, attics and the yard.