A quick trip to your local home improvement store (or even better, shop online and pick up with ease), you can get your house ship-shape ready for the market and pass inspection reports with ease.
Door knobs - be sure that you have a deadbolt on all exterior doors. This is code and recommended over a keyed lock; for safety reasons, as it is easier to turn a knob then find the key for the lock. Prices from $10-$100 depending on finish and style. You can install yourself with a phillips screwdriver or drill.
Switchplate covers! Take a look around you property and you may be surprised the number of missing switchplate covers. Perhaps you painted years ago and never put them back on. OR you painted over top of them and they don't look their best, so you may wish to replace it. Look in the back of cabinets, behind furniture/refrigerator, up high - sometimes switches/outlets are close to ceilings. Then pick white or almond and add or change them out. You can get packs of 10 of basic colors, for cost effectiveness.
Is your tub stopper or shower drain cover missing? This may not be an issue for your if you are not a bath taker, but the new owner may appreciate being able to keep water from going down the drain. Shop the bath aisle of your nearest hardware store and spend $2-10 on a stopper. It doesn't have to the be the metal cover that likely came with the tub.
Check behind those doors. Are there dings or holes because the wall became the door stopper? Add door stoppers and/or place a round plastic disc where the door knob hits the wall. Door stoppers can be installed (hand screwed in) on the wall where the bottom door meets the wall. Or use a hinge pin door stop which is installed at the top of the door hinge.
And, take a look at the wooden fence gates. If there are any missing parts such as latches, screws, hinges, go ahead and replace them or screw them in properly. This is also a relatively inexpensive task with latches costing as low as $5 to hinges costing less than $20.
And finally, change burned out light bulbs. Preferably make all bulbs match in ceiling fixtures and vanity fixtures.