An Open Mind and An Orderly House

As a seller, you should be aware that same-day and even last-minute requests for showings are common.
A seller with a '24 hour notice to show' stipulation cuts himself out of a good chunk of the buying market. The only standard hefty lag time that should be necessary is when you must give ample notice to a tenant. If you do find it necessary to restrict showing times, you must understand that it might inhibit your ability to sell the house.
Keep it Flexible

Most agents do try to arrive within the scheduled showing time, but sometimes it isn't possible. They may get stuck in traffic, or the house they saw prior to your showing took longer than expected. It happens, and sometimes it happens too late to be fixed by a phone call.
I encourage my sellers to stay away from home a little longer than they think is necessary, just to make sure they don't interrupt a showing.
Sellers Who Want to Be Present
This is nearly always a bad idea. Sellers think agents and buyers won't be able to find everything, that they must be there to point out important features. Truthfully, most just want to be present to see buyer reaction firsthand. You need to understand that at the very least buyers feel uncomfortable when they are present, and that it can actually kill a sale. Buyers often won't even open closet or cabinet doors when the seller is present. If home buyers cannot view the house comfortably, they'll hurry up and move on to the next one. Sometimes sellers want to talk, and not just about the house. You never know when a buyer will be turned off by the mood of the seller, or by a statement the seller makes. Buyers are there to look at the house, not chit chat about hobbies or the weather or worse--politics and other controversial topics. If you must be home during a showing, go outside or stay put in one location, rather than wander around with the agent and buyers.
Neat and Tidy

Not everyone makes his or her bed everyday, but when selling a home, it is recommended that you develop the habit. Pick up papers, don't leave empty glasses or dishes laying around, and keep the furniture dusted and floors vacuumed and swept. Try your best to make it look like a model home--furnished, but no one lives there.
Lighting

When you know someone is coming by to tour your home, turn on all the indoor and outdoor lights ?? even during the day. At night, a lit house gives a "homey" impression when viewed from the street. During the daytime, turning on the lights prevents harsh shadows from sunlight and it brightens up any dim areas. Your house looks more homey and cheerful with the lights on.
Fragrances

Do not use scented sprays to prepare for visitors. It is too obvious and many people find the smells of those sprays offensive, not to mention that some may be allergic. If you want to have a pleasant aroma in your house, have a potpourri pot or something natural. Or turn on a stove burner for a moment and put a drop of vanilla extract on it. It will smell like you have been cooking.
Controlling Pets
If you have pets, make sure your listing agent puts a notice with your listing in the multiple listing service. The last thing you want is to have your pet running out the front door and getting lost. If you know someone is coming, it would be best to try to take the pets with you while the homebuyers tour your home. If you cannot do that, It is best to keep dogs in a penned area in the back yard. Try to keep indoor cats in a specific room when you expect visitors, and put a sign on the door. Most of the time, an indoor cat will hide when buyers come to view your property, but they may panic and try to escape.