Get your mower ready: Make sure your lawn mower is ready before you need to use it. Bringing it in before the start of the season will ensure you won't have to wait along with everyone else in your neighborhood. Note: Don't overlook sharpening your mower's blade. For the cleanest cuts -- and healthiest-looking lawn -- sharpen the blade at least once a year.
Start a new lawn from seed: Fall is the best time to sow seed for a new lawn. If you can't get to it at the end of season, spring is the next best time. Don't wait too long; your lawn needs to get established before summer arrives.
Prevent crabgrass from being a problem: Annual weeds, such as crabgrass, grow from seed each spring. Use a well-timed application of pre-emergence herbicide to stop them from growing at all. A good guideline is to spread the pre-emergence herbicide as forsythia blooms in your area start to drop.
Aerate compacted soil: Most lawns have trouble growing in compacted soil (many weeds, unfortunately, thrive in it). If you need to or want to aerate, do so in spring -- when your grass is actively growing.
Begin mowing: Allow your grass to grow no more than 3 inches tall before you start mowing. The best general rule to follow is that you want to keep most grass types at least 2 inches tall -- this height helps the grass ward off weeds and withstand summer drought. But you don't want to remove more than a third of the total grass height at any one mowing. Removing too much stresses the grass.
Apply fertilizer: If you feed your lawn a couple times a year, a light application of lawn fertilizer in spring helps get your grass off to a great start. Wait to fertilize until your lawn needs mowing for the first time. Do a light application and use a slow-release or organic fertilizer; don't try to feed your lawn for a quick green-up; this doesn't usually work and can harm your grass.