Part of the draw to sell in the spring is an expected market. That market is due in-part because homes and yards are all spruced up and fresh and looking their best. If you prep now, your yard will reward you when you sell in the spring.
You might have a mower that does this for you, if not you'll have to do bit more leg-work. But, the mulch (grass clippings and leaves) are nitrogen and carbon-rich materials that return nutrients to the soil. Be careful though. You can damage a lawn by mulching too much. (Like that time when you skipped mowing a few times....and the leaves!!!) Don't overdo it.
If the soil is compacted or compressed, it hurts the grass health (and ability to thrive). By aerating, you let nutrients get down in the soil. There are push aerators and even shoe contraptions to get the job done. Because Indiana has a lot of clay down under, aerating can really make a difference!
Keep those edges and areas around bushes and landscaping neat and trimmed. If unwanted trees sprout up, try to remove the roots as well to keep a nice continuity. Fall is a great time to do some patching/repairing. Grab a mix from the store and follow the easy instructions!
Last and maybe most important: keep on mowing. Experts say try not to cut more than a third of the length of the grass in a mowing. And, for the last couple mowings of the season - go to the lowest settings on your mower.