1) Clean it !
Absolutely get it clean even if that means painting, replacing and washing windows, replacing or cleaning the blinds, getting the outside power washed, hiring a cleaning service, scrubbing the kitchen including the stove. Make this house cleaner than the day you moved in!
2) Bright, cheerful, open!
Open the drapes, use the highest wattage light bulb allowed that is safe, leave the blinds open or pulled up. Let the sunshine in! Dark, gloomy houses take a long time to sell. Make yours a happy place to be in!
3) Clutter be gone!
Box it up, store it, do whatever is necessary but get rid of the clutter! Make sure all the rooms, especially the kitchen, bathroom, and closets are free of clutter. Notice if your furniture is too large for the room size. If so, think about putting some in storage or at a friend's house. Claustrophobic homes are not easy to sell.
4) The bathroom rules!
Throughout the house, but certainly in the bathroom, make sure faucets don't drip, tile isn't chipped, sink and tub are not crazed, mildew is not present, mirrors are not cracked or chipped, and caulking is not needed! The bathroom is the single, most personal room in the house. No potential buyer wants to feel they are moving into someone else's personal space. They want the illusion this room was never used by others!
5) Outdoors IS the first impression!
If necessary, hire a gardener to beautify your lawn. Add some colorful flowers, check the screens, the soffits, roof, and driveway, make sure they are in excellent condition. Make the outside as neat as the inside, including the garage.