1. Confirm that the water, electric and gas service are on, with gas pilot lights burning.
2. Ensure pets won't hinder the inspection.  Tell your agent about any pets at home.
3. Replace burned out bulbs to avoid a "Light is inoperable" report that may suggest an electrical issue.
4. Test smoke and carbon monoxide detectors, and replace batteries where needed.
5. Clean or replace dirty HVAC air filters. 
6. Remove stored items, debris and wood from foundation.  These may be cited as "conducive conditions" for termites.
7. Unlock areas the inspector must access - attic doors or hatches, electrical panels, water heaters, closets, fence gates and crawl spaces.
8. Trim tree limbs from roof and shrubs from the house to allow access.
9. Attend to broken or missing items like doorknobs, locks, windowpanes, screens, gutters, downspouts and chimney caps.

By checking these and other areas in and around the house you are being pro-active and your real estate agent will thank you.