If you are putting in a completely new lawn or just maintaining your existing lawn, you should always pay attention to the factors that affect the way your grass will grow. You need to think about how much sun and shade the grass will be getting. Consider poor drainage, wind, and heat stress when picking varieties of grass. Think about how much maintenance you can handle; low, medium, or high. Think about the cost of everything. A low-maintenance lawn is better for a smaller cost. If you want your lawn to be thicker, greener, more fine bladed, and more vigorous and stress tolerant, the solution is to reseed it with new, improved variety. You don't exactly have to dig up your old lawn, just overseed the existing grass with new seeds. First you have to analyze the condition of your current lawn. If it has less than 50 percent good grass, the best thing to do is remove it all and start over. But, if more than 50 percent is strong, overseeding is a good option. Try to figure out what made the existing grass weak; shade, drought, insects? Then you can pick the kind of grass that prevents those problems. Now, pick the right time for germination. Fall is best for cool-season turfgrasses and spring is best for warm-season grasses.