To get the most out of your lawn, you need to research and really understand what you are working with. What kind of grass you have and what does it need... How much water, Is it resistance to pests, How about tolerance to shade? If you’re starting from the very beginning then you need to do some research to identify the best grass type for your climate and soil type where you live. If you have an established lawn and it needs a lot of love, then you're probably better off consider replanting with a new, more suitable type of grass.
Once you have a basic understanding of the aforementioned questions, the next step is to test your soil. Inexpensive soil pH testing kits are available, or you can use litmus paper. You can then have your soil’s fertility tested by your state's cooperative extension service (Orange County Link embedded) or a commercial soil-testing lab. Your local nursery can make recommendations based on the test results.
You may be surprised to find that most homeowners water too often with too little water. The key is to water thoroughly and only when needed, when the grass begins to wilt, the color dulls and footprints stay compressed for more than a few seconds. Another surprise to most... Drip hoses are the most efficient method. From there... the next best thing is an in-ground automatic sprinkler system. To evaluate how long sprinklers should run, turn them on and time how long it takes for the water to penetrate four inches into the soil (open up the ground periodically with a shovel). Water only in early morning or evening once the heat dies down, and yet not too early that it will cause frost or damage.
Now that you have the watering down... you must make a commitment to mow frequently, but with that you must understand that frequent mowing makes grass require more water. Sharpen your mower’s blades frequently to get a clean cut, and never mow when the grass is wet. Cut no more than 1/3 of the grass’s length at a time. Leaving your lawn slightly long will produce healthier, more pest-resistant grass.
Now... you really want to step it up, another great ideas is to aerate your soil every year. This helps to clear out thatch, which is the dead, un-decayed material at the soil line. This material adds to a number of lawn problems. Before aerating, be sure to give your lawn a good, hard raking to loosen up and remove the thatch.
Now that your lawn really looks good... to keep it looking good, you need to feed it, and by feed it we mean fertilize. The best fertilizers are organic, slow-release types. Your soil's test results will indicate specific organic fertilizer recommendations. Although you can spread fertilizers by hand, you'll get more uniform coverage with a spreader (drop or broadcast type). Make two passes at opposite angles. Water thoroughly after applying fertilizer or apply it before an expected rain, unless the directions state otherwise.
Lastly... to keep down on additional problems, you may need to apply weed-killers. Only do so when weeds first start to grow, before they go to seed. Apply these products with a hose-end sprayer or with a garden spreader. For additional gardening tips, contact your local professional, and they will point you in the right direction.