Sunlight is an important factor in maintaining your lawn. Most common grass varieties (fescues, Kentucky Bluegrass, perennial rye) will only really stay lush and green in full sun, though most will tolerate some shade. If your property is partially shaded all day or receives less than 4 hours of full sun a day, you should consider sowing a variety that is more suited to shade such as Tall fescue 'Rebel', Kentucky bluegrass 'Park', Red fescue 'Ruby', zoysia matrella, St. Augustine or Chewings fescue. You may also want to consider Gardens Alive!'s Turf Alive! seeds.
Keep in mind that your landscape changes over time -- trees grow, old plantings die allowing more sunlight in, etc. You may find over the years that you need to reseed your lawn with a grass variety more appropriate to the new conditions or sow different types in different areas such as shade, high-traffic and full sun.
A few Natural Products from Gardens Alive:
All Natural Weed and Feed for your lawn
Natural Pet Products