Remove sources of food, water and shelter for the rodents.
Clean up potential food sources such as trash, fallen fruit from fruit trees, or pet food. Consider cutting back excessive vegetation that is growing on or near your building. For example, ivy provides a perfect habitat for mice and rats.
Seal out rodents.
Mice can fit through gaps as thin as a pencil. Seal up gaps of that size of larger with 1/4" screening, escutcheon plates, and/or metal wool (copper or stainless steel). Purchase a door sweep to seal large openings under doors.
If rodents persist, use snap traps.
Use traditional snap traps if you still have a problem. Use lots of them; place them on rodent trails at night, and pre-bait (without setting the trap) for the first day. Remember to keep pets and children away from trap-laid areas.
Rats and Mice Factsheet (Our Water, Our World)
“General measures for keeping out uninvited guests.” (University of Arizona)