Living in an area considered to be a "transition zone" between warm and cool climates, it's not easy to grow tall fescue. I try to overseed my lawn every year in early September. There is a Home Depot near me that rents a slit seeder. I usually have a landscape company do a core aeration because it's only about $90. Then I rent the slit seeder from HD for about $65 for four hours. I've tried just tossing the seed after aeration but it's definitely inferior to using the slit seeder. The slit seeder also slices up thatch and weeds for an added bonus. If I feel energetic I might buy a couple yards of compost and spread it lightly over the lawn right after seeding, which is a lot of work. After seeding I water the lawn everyday for about nine days, and every two days for another week or so. By October my lawn looks like a million bucks, and will come back looking good the next spring too.