Most buyers nowadays are looking for houses that are ready to move in. They don't want to move in and have to change carpeting, or redo cabinets or counters, or in some cases they don't even want to paint. So it is a good idea to do basic fix-ups and routine maintenance items to allow them to just move in. It can also help get you a higher sales price.
It is best to go room by room and look at each aspect of each room and figure out what needs repairing. This starts at the basic things such as outlet and light switch covers, to baseboard trim repainting, to carpeting. Make sure light switches work, and that outlets work. Check that the furnace vents are clean, and that radiator valves don't leak. Open closet doors, lube rollers and latches. Make sure doors latch correctly and don't squeak. Replace any burnt-out light bulbs with the highest wattage allowed in each fixture. If you have ceiling fans, make sure they work on all speeds, and that they don't wobble. If they wobble, re-balance them. Polish floors, clean carpets, and the like.
In the kitchen there are several other items besides the basics, that need checking. Make sure all appliances work, as well as their respective light bulbs. Clean each appliance. Check that there are no leaks anywhere, not the faucet, not under the sink. Test GFCI outlets. Make sure the sink sprayer works appropriately. De-grease the walls and cabinets around the stove or oven. Lube the bearings on the cabinet drawers. Make sure that all 4 burners (or more if you have them) light easily and work appropriately. Re-caulk around the sink and faucet if needed.
The main thing about bathrooms is that they are clean and bright. Change the light bulbs to the maximum allowed in each fixture. Re-caulk or re-grout if needed. If you have vinyl flooring, make sure it isn't peeling in the corners. If there is loose wallpaper, reattach it or strip it all off. Clean the shower head, or replace it. Make sure the toilet doesn't leak or drip which may require replacing the flapper. Make sure the faucets don't drip or leak. Check for leaks under the sinks.
Buyers like to see that utilities have been maintained. On the furnace, change the filter and vacuum and dust the exterior. Make the furnace appear well maintained. The top of the water heater always collects a lot of dust. Wash it off and make it clean. If you have a water softener, fill it up with salt so that it is full. Don't let the buyers see the bottom of the tank filled with brine water. If you have a humidifier, clean the screen, or better yet, replace it altogether. On electrical panels, make sure there are no holes or gaps. If you have any holes, plug them with the appropriate plug. Same with missing circuit breakers, fill the empty slots with covers. On the water main, make sure there aren't any leaky valves or drips. Also locate the sewer clean-out and make it accessible for the inspection.