Dear Peggy: A fall aeration is a good idea to relieve soil compaction, allow more air and water into the soil profile and encourage deep root development. If your lawn is thin in spots or you have had disease in your lawn, over-seeding is a way to recover and thicken your lawn again. If done, a blend of hybrid, diseases resistant grasses adapted to your area should be used. A fall fertilization could also be helpful.
Best of luck with your lawn,
Richard