1. Prevent weeds before they come up. 
You can stop weeds from gaining a roothold in your lawn before they even germinate by using a pre-emergent herbicide. This type of product controls the dreaded crabgrass, as well as other hard-to-eliminate weeds, by stopping their seeds from sprouting in your lawn. Use a pre-emergent herbicide early in the spring.

Note: Watch the forsythia and lilac shrubs in your area. When the blooms start to fade and drop off the plant, it’s time to apply a pre-emergent herbicide.

2. Eliminate broadleaf weeds once they’ve sprouted. 
Broadleaf weeds are the big weeds that are immediately obvious in your lawn: the bright-yellow faces of dandelions (and their scatter-in-the-wind seeds), white-flowering clover and big-leaf plantain are all pretty visible. To treat, apply granular weed control products. If there are just a few offenders, you can remove them by hand.

Note: Wait to apply until there is heavy morning dew. Why? Because weed-and-feed granules need moisture to stick to weed leaves—and a dewy morning provides that for you. You can also turn on lawn sprinklers for a half hour to get the same effect.
Note: Are you watering enough? Try the soup can test. Set an empty can next to your lawn sprinkler. When there is about ½ inch of water in the can, it’s time to turn off the sprinkler.

3. Mow high and frequently. 
Mowing your lawn too short may seem like a time-saver, but this can damage your grass as well as allow weeds to take root. Keeping your lawn a bit taller results in healthier grass. The general rule of thumb is: Never cut off more than a third of the grass blade.

Note: Set your mower as high as it will go—up to 3 inches—and keep it there all summer.

4. Sharpen your mower blade. 
A dull blade tears the grass, resulting in a ragged edge that makes the overall lawn look grayish brown. Sharpen the mower blade when it shows signs of wear—or at least once a mowing season.

Note:  The size of your lawn and the frequency of mowing will dictate how often you should sharpen your blade. Take a look at a grass blade after mowing. If it is shredded or frayed, it’s time to sharpen up.

5. Water in the morning. 

The best time to water your lawn is the early morning because the sun will help dry the grass. Nighttime watering can result in prolonged moisture on the blades, which can open the door to some diseases. It’s better to water less often but for prolonged periods. Just wetting down the grass isn’t watering the grass. You need to soak the lawn so the soil moisture penetrates down several inches.

Note: Are you watering enough? Try the soup can test. Set an empty soup can next to your lawn sprinkler. When there is about ½ inch of water in the can, it’s time to turn off the sprinkler.

6. Feed your lawn. 
What do lawns like to consume? Nitrogen is the most important nutrient – look for a mix of fast- and slow-release fertilizers that will green up your lawn quickly, then feed it over time. In the north, feed in fall and spring. In the south, feed in spring and summer. Don’t feed dormant grass (drought can cause grass to go dormant in summer) because it can’t take in nutrients.

Note: More is not better. If you put too much nitrogen on your lawn, you’ll burn it. Read the label and follow the application directions to a T.

7. Train Spot. 
If you have a dog that spends any time in your yard, your lawn will show it. Large yellow and dead spots in your lawn will be giveaways. The nitrogen in dog urine is the culprit. Encourage your dog to use just one spot in the yard. Make a gravel or mulch area where your dog can do his business without spotting the lawn.

Note: Yard-train your dog, in the same way, you house-trained him. Walk him out to the area you want him to use and use treats to reward good behavior.

8. Reseed sparse lawns. 
If your lawn is a little thin in areas, you can seed over the area to help lush it up. Fall is the ideal time to reseed cool-season grasses. Plant warm-season grasses in late spring.
Note: Make sure you don’t apply a pre-emergent herbicide at the same time you plant seed; it will stop your grass seedlings from growing.

Article from: https://donthelawnman.com/index.php?option=com_k2&view=item&id=11:8-easy-tips-for-a-perfect-lawn&Itemid=120