If you have any pets, get them out of the house. Some people wal into a house where a dog or cat has been, and juat turn around and walk out...
even if they have pets, they don't want to live with someonelse's pet smells...
Also, this is the time to really cut back those shrubs. People want to look at the house, not bushes. Also, if it needs it, a coat of paint on the outside trim can't hurt...Some work, little cost, lots of curb appeal.....
Steve