First the bad news: if you neglect spring lawn care (and related concerns pertaining to your mower), you could end up paying for it the rest of the year. Now the good news: spring lawn care doesn't entail nearly the amount of work that you'll have to invest in mowing alone throughout the summer months.

TIP #1: Raking
Raking will be your first task of spring lawn care. Raking is for more than just removing leaves: it's for controlling thatch, too. A thatch build-up of more than 1/2 inch is considered excessive.

When you rake the leaves, make the effort to rake deeply. Don't just skim the surface, so as to remove the leaves. A deep raking will remove thatch, too, allowing you to kill two birds with one stone. Even if you followed this advice in fall, a spring raking is still recommended: it will remove grass blades that died over the winter - dead blades that are just waiting to become thatch!

Tip #2: Liming
Besides compaction, the presence of moss plants also signals acidity. But grass likes a neutral soil pH. You can solve this problem by liming your soil.

But first send a soil sample to your local county extension to determine the extent of your soil's acidity. The county extension will also be able to advise you on how much lime per square foot you'll need. Apply the lime using a lawn spreader. If your lawn has been doing fine and shows no signs of suffering from acidity, don't apply lime. Liming is only a corrective measure, not a preventive measure. A soil, that is too alkaline, will also cause you to have lawn problems, so too much lime is as bad as not enough.

TIP #3: Over seeding
Is your lawn riddled with bare patches due to dog spots, heavy traffic or neglect? If so, you may need to apply grass seed to fill in those bare patches. This solution is known as "over seeding lawns." Apply a slow-release nitrogen fertilizer when you over seed. Five weeks after the grass germinates, apply a quick-release nitrogen fertilizer. Even though the Fall is the preferred time for over seeding lawns, because our situation is dire, it is recommended.

TIP #4: Fertilizing
Many experts recommend a lighter feeding in spring and a heavier one in fall. Too much fertilizer in spring can lead to disease and weed problems. In addition to the above tasks of spring lawn care, don't forget weed control and making sure your mower is ready for the mowing season.

Taken from: http://landscaping.about.com/od/lawns/a/spring_lawns.htm