Research says that chemical fertilizers, herbicides and pesticides used in lawns can be carcinogenic, and increase the presence of harmful nitrates in drinking water wells. An easier healthy alternative is to go organic.

To get the lushest lawn possible, research well on the varieties of grasses that do well in your climate before planting the lawn, and select the right mixture of grasses. Also figure out the watering time required, so that the roots are strong and less vulnerable to disease. Aerate the lawn so that compacted soil is loosened and water does not run off, but soaks into the ground, this will eliminate the need for chemical fertilizers.

Mulch is a layer of organic or synthetic material that will suppress weeds. 

If you subscribe to any newspapers, you can use your piles of old newspapers to block weeds from growing on your lawn. Start by placing 2 to 6 sheets of newspapers on the soil around your lawn plants. Add a 1-inch layer of grass clippings on top and cover it with soil.

Using newspapers for Mulch has been proven to be very effective, and it's also good for the environment because you are recycling :).