Renovation, seeding or overseeding are best done in the fall. For peak performance, annually top-dress lawn with 1/4" compost.
Use a certified first class grass seed
Including clover* in your seed will provide your lawn with nitrogen. Plant only as much lawn as you need and only where it will grow well. A diversity of other plants can be used to improve the overall beauty and quality of your lawn.
*Clover has a tendency to attract bees, especially when not mowed to remove the flowers. If you have allergies to bee stings, avoid planting more of it in your lawn.
Water deeper, less often
Wet the soil down to the full depth of the root zone, at least 6 inches deep. This is roughly 1" of water collected in a cup under the sprinkler. Water when the grass needs it, not on a schedule. It needs to be watered if the top 6 inches of soil is dry. Do not water in the middle of the day, when evaporation loss is greatest and water is wasted.
Set your mower to a height of 3"
Keep the mower operating properly and the blades sharp. Only remove 1/3 of the grass blade at a time. Leaving the grass clippings on your lawn will provide it with 40% of the nutrients it needs. In late fall, cut grass shorter for easier fall raking and cleanup.
Correct the pH
Apply lime only based upon soil test recommendations. Soil tests can be obtained from the UMass Soil Testing Lab, (413) 545-2311, www.umass.edu/plsoils/soiltest. The ideal pH of a lawn is between 6.8 and 7.0 

Stop! Go cold turkey!
The lawn is probably addicted and may show withdrawal symptoms.  Pesticides kill the beneficial organisms in your soil. It will take some time to re-establish a balance.   
If thatch is greater than 1/2 inch, dethatch
Thatch is a mat of dead roots and stems that accumulates at the surface. Excessive thatch is caused by quick-release nitrogen fertilizer, poor mowing and watering habits, and low microbial activity. Excessive thatch blocks the growth of healthy grass and provides a medium for insect pests to live.
Recover with compost
The quickest way for a "junkie" lawn to recover is with two applications (1/4 inch each) of good quality organic compost. This will naturally control thatch by increasing the life in the soil. Once you start an organic program, be patient, you will soon see results.

Water only when needed, not on a schedule