Staple monofilament in place. If the door opens out, the spiders fall. If it opens in, the spiders fly. Monofilament is also handy for creating rocking chairs inhabited by invisible specters when tugged on by an unseen conspirator in a bush or behind a door. Brown packing paper that's been wrinkled and attached to the walls, bunched up in places then painted with bold stripes of gray and black gives a run down appearance.
Some boards placed over windows adds to the effect.
Flats used to stack cargo are a good source of wood. Check with home improvement stores. Spanish moss hanging from around the eves of the house also adds to the eerie dilapidated effect. Get some water based paint available at art supply houses, and paint a portrait on the outside of your window. Paint eyes on the inside.