Shampoo the carpets or carpeting. Put new washers in all dripping faucets. Throw away the torn shower curtain and put up a new one. Contribute whatever remains to the next trash pick-up. Turn off all blaring stereos and TV sets while the house is being shown.
Soft music is more desirable.
Water all dying plants or get rid of them. Adjust all doors, including closets, and windows so they can be opened and closed easily. Replace broken tiles on walls or floors and re-paste loose or dangling wallpaper. Make the beds and keep all clothes out of sight. Keep the kitchen counter tops and sink clean and clear.