Take a perfectly lovely room and cover the furniture with sheets or blankets. White is best, but other solid colors or subtle patterns will do in the dark. If you have old curtains, the sheer material is very effective over lamp shades. Be sure the fabric is not touching the light bulbs!
Start by experimenting with your lighting. Try low-wattage light bulbs or orange flame bulbs.
Add the sheers over the lamp shades and experiment with the lamps on and off.
Add the sheets to the furniture.
Dim the lights.
And presto! A creepy abandoned room!
Be careful about the use of candles in a room covered in fabric. It is best to create your lighting effects with lightbulbs and battery-powered candles.
If you have rugs in the room, removing them will contribute to the abandoned house look.
After the party, wash the sheets if needed and put them away. It's that simple.