Mow the lawn short
Remove rocks, sticks, and debris
Mark low spots and high spots
Cut and remove high spots with a shovel if needed
Fill low spots with a topsoil and sand mix
Spread the mix evenly with a rake
Use a lawn leveling rake or drag mat to smooth the surface
Lightly water the area to help settle the soil
Repeat filling and smoothing until level
Reseed bare areas if needed
Water regularly until grass is established
Avoid heavy traffic until the lawn is settled