Mark the low and high spots with stakes or spray paint
Remove rocks, debris, and dead grass
Mow the lawn short
Test drainage and soil type
Fill low spots with topsoil or a sand-soil mix
Spread soil evenly with a rake
Compact the filled areas lightly
Add soil in thin layers if needed
Recheck the slope and level with a long board or level
Grade the yard so water flows away from structures
Seed or lay sod over disturbed areas
Water the area lightly
Repeat filling and leveling as the soil settles