Fertilize the lawn if you didn't do so last month.
Mowing at the right height helps keep turf thick and healthy. Time mowings so you're only ever removing one-third of total blade growth. Follow this guide to mowing height.
Fine fescue: 1-1/2 to 2-1/2 inches
Kentucky bluegrass: 1 to 2-1/2 inches
Perennial ryegrass: 1 to 2-1/2 inches
Tall fescue: 1-1/2 to 3 inches
Bermudagrass: 1/2 to 1-1/2 inches
Buffalograss: 1-1/2 to 4 inches
St. Augustine: 1 to: 3 inches
Zoysia: 1/2 to 2 inches