Here is a list of things to consider doing in-between tenants.  I basically think to myself: What would need to be done in the next five years?   After all, a tenant could stay a long time, or you could find yourself with very little time between renters.

• Clean the washing machine, dryer, and dishwasher.  If the washing machine is front-loading, check for mildew, and don’t forget to leave the door open
• Clean the refrigerator.  Don’t forget to vacuum the coils
• Clean the filters in vent hoods and cook tops
• Clean all air ducts and the dryer vent
• Deep clean carpets
• Clean out drains.  Run an enzyme-based drain cleaner to help prevent future problems
• Clean and seal grout, both flooring and bathroom tiles
• Clean the shower door.  If the door gets spotty from hard water, use a protectorate to make this easier for next time
• Replace toilet seats.  Check toilet plumbing for issues
• Replace batteries in smoke detectors and carbon monoxide detectors.  Consider using 10-year batteries.  If the detectors are more than ten years old, replace
• Install carbon monoxide detectors if needed
• Hire a pro to do a furnace and a/c check
• Take photos of EVERYTHING