Having a good soil is the ideal foundation for a picture-perfect lawn and where everyone should begin in their quest for the ideal lawn. You can get a green looking lawn by dumping fertilizer on it, but unless the soil is healthy, the fertilizer is just a short term fix. Spending some time creating a healthy soil will go a long way in creating a healthy lawn that requires less fertilizer, and less watering.
If you have a bare plot of soil, or are ready to re-establish a new lawn, then you are in an ideal place to get started. If you already have a lawn in place and don't want to start over, then the process is a little slower, but it is still doable.
Healthy plants grow in healthy soils. Plant problems (disease, weeds, insect infestations) can often can be attributed to poor soils. Most healthy plants can fend for themselves in the world if given a fighting chance by providing a healthy environment for them to grow. Take away that healthy environment and they become weakened and these opportunistic pests can over take them.
Therefore you want to make sure your soil is always improving. You want to make it a haven for microbes. Microbe activity is the key indicator.
The best way to keep the microbes happy is to give them plenty to eat in the form of organic matter. You obviously don't want to drown them out, or kill them with chemical contaminations.
If standing water is a problem, take steps to improve drainage. Don't block natural drainage pathways by creating a landscape that traps water in localized spots. The landscape should have natural paths for water to follow without pooling. Water always moves downhill—just don't block that movement by putting in a raised flower bed across its natural path.
Next, avoid using insecticides in the lawn and landscape. Many insecticides kill everything it comes in contact with. Be absolutely certain of what you are doing before spraying any insecticide as the results can be far reaching and quite devastating to the health of your entire soil causing many more problems for you than a few insects could ever do.
Every year you want to recycle organic matter into the lawn. This can be done in multiple ways.
Don't bag lawn clippings. Lawn clippings provide a regular addition of organic matter into the soil— and it's free!
Add an annual top-dressing to the lawn. This is really a big jump start to improving your soil. The thin layer of top-dressing adds a lot of natural organic matter into the top layer of soil. In time, this layer will develop into several inches of good friable loam that will provide ideal growing conditions for your lawn. The above photograph shows large commercial top dressing equipment making an application to a large field.
Having a healthy soil means you'll have a thick healthy lawn requiring less fertilizer, fewer weeds, and less opportunities for disease and insect problems. Begin with the soil first and the rest will almost take care of itself.