Don't leave bird seed in feeders or on the ground overnight.
Don't put unsecured garbage outside at night.
If you have a pet door, securely close it at night.
Trim overhanging branches that provide easy access to your roof for squirrels and other wildlife.
If you have a chimney, make sure that it has a secure cap. Chimneys without caps are open invitations to birds and raccoons looking for "hollow trees" in which to raise their young.
Thoroughly inspect your roof, eaves, and siding for signs of damage. Cover attic vents and other roof openings with heavy-gauge, rustproof wire mesh.
Cover foundation vents with heavy-gauge, rust proof wire mesh.
If you have a deck, install an L-shaped barrier to prevent animals from digging underneath it.