Use higher watt light bulbs. Fix leaks and drips. Use neutral paint colors like Kelly Moore Navajo White. Prepare your kitchen to look like that of a model home. No refrigerator magnets, no small appliances left out, no personal artifacts,messages etc.
Bathrooms have to sparkle.
Mildew and stain are killers here. Try new towels and bath mats. Store any extra furniture. Remove posters and adhesives from walls and doors. Lights operable and as bright as possible.