If you haven't already, get your mower ready to go this month. Change the air filter, replace oil and spark plugs, and sharpen the blade. Add fresh gas, and you're ready to go.
At lower elevations, when forsythia blooms, apply crabgrass preventer. It works by preventing seeds from germinating, so don't apply if you plan to seed bare patches. If you do apply crabgrass preventer, seed bare patches in fall.
Aerate your lawn in spring, before seeding or fertilizing (if you're doing those things). Typically, you want to aerate every two or three years to reduce compaction and thatch. Rent a machine that removes plugs of soil or have a lawn service do it. You can also aerate in fall.
Bluegrass, ryegrass, fescue, wheatgrass: Mow to a height of 2-3 inches.
Buffalograss and blue grama: Mow to 2-3 inches or leave unmowed.