Those who have been putting off seeding bare and dead spots in the lawn because they "wanted to see if the grass will come back" have reached the end of the line. By now, most of Ohio lawns have experienced sufficient rainfall to green-up and if there are spots that aren't green, the grass isn't coming back! Take care of re-seeding quickly in order to take advantage of the cool nights and warm days of late summer and early fall. Grass seed germinates best in this type of weather and needs to have sufficient time to grow in the fall in order to be ready for winter's cold.
In lawns containing mostly Kentucky bluegrass, small bare spots (sliver-dollar-size or less) will likely fill in this fall as growth resumes. In turf type tall fescue lawns, however, since these don't spread by rhizomes, these spots will not fill in and should be repaired. Bare spots that are not reseeded will quickly be overtaken by weeds since there is no competition with turf.
When renovating dead spots, be sure to select the grass species that matches or blends with what is already in the lawn. For instance, if one reseeds a Kentucky bluegrass lawn (fine blades) with a turf type tall fescue (thicker blades and clump growing), one will definitely notice the difference in the new areas and the rest of the lawn.
In order for the new grass to thrive (and not just survive) make sure the seed is in contact with soil and exposed to sunlight. Maximum germination of turfgrass seed occurs when the seed receives full-sun. In other words, rake to remove dead plants and to loosen the soil before depositing seed. Additionly, adequate moisture is essential to ensure new seedling survival; don't let them dry out during the establishment period.
A "starter" fertilizer should be applied at the time of seeding or shortly after seeding. DO NOT use a fertilizer that is combined with a weed control product, unless the product is clearly labeled for use on newly seeded lawns. While fall is an excellent time of the year to control broadleaf weeds, new grass seedlings won't tolerate many types of turfgrass herbicides. Therefore, worry about getting the seeds established this fall and start a weed control program next spring. EXCEPTION! There is one exception to spring weed control programs after fall seeding - do not use a spring crabgrass control product on newly seeded turf unless it's a type of kind of crabgrass preventer that is labeled for seeding lawns such as siduron which doesn't harm turfgrass seedlings.