Realtor.com has a checklist and several article on prepping your home for sale, as does Money magazine and others - google a search term list this for more ideas - house sale preparation.
Common suggestions from Realtors, and things potential buyers turn away from if undone:
1) dirty / stained / cracked windows
2) significant debris or moss on roof, or visibly significantly deteriorated roof
3) damaged/missing steps or porch boards, and cracked/highly uneven walks
4) weathered/stained (wood) or cracking/broken (brick/concrete) porch
5) untrimmed, scraggly bushes and leaves/debris, or trashy or unmowed yard, especially near house
6) debris/junk/junker cars in yard or drive
7) peeling/cracked paint on house, especially on portion visible from drive and approaching front door
8) dirty pool
9) unwashed / unplowed drive and approach walk
10) dirty house, especially bath, kitchen, carpets
11) any odd smells in house - smoking, pet, mold, stinky plant pots, strong cooking smells, diapers, litter box, strong pot pouri
12) crowded rooms - kick unneeded furniture and possessions to a storage locker or have moving company pack and store temporarily while getting ready to move, ifnot moving till sold
13) dirty/stained walls - paint if bad, otherwise wash with TSP
14) dirty grout
15) visibly worn/broken flooring
16) corroded or dripping faucets and tub/shower fixtures
17) non-functioning appliances, lights
Almost all of of these you can do yourself unless you have medical/disability issues.