Once your lawn is well established, it's not necessary to overseed each year. For new lawns, the surface of the soil should be tilled 4 to 6 inches deep so the soil isn't compacted. Soil compaction will prevent air and water from getting to the turf's roots. This also is an ideal time to till in any nutrients a soil test has indicated are needed. You can also add organic material to improve the texture of the soil, help its water retention and aerate the soil.
Organic matter helps aerate clay-heavy soils and helps maintain moisture in sandy soils.
Aeration should be done every two to three years, depending on how the soil compacts. Aeration, which is typically done with a piece of equipment that has spikes to pull out plugs of the soil, allows water, nutrients and seed to get into the soil instead of just lying on top of the soil. In addition to the many fescue choices, commercially marketed blends, such as Southern Belle, incorporate several fescues. Seeds with one of the two Virginia-Maryland labels have been tested and deemed suitable for local growing by research done at Virginia Tech and the University of Maryland. You can find warm-season grasses in sod form for instant lawns.