how do i level a yard without making a mess?

Mow short first. For small dips, top dress with a mix of sand and topsoil, spread it with the back of a rake, no more than about 1-2cm at a time so the grass grows through. Water it in and repeat after a few weeks. Deeper holes, cut the turf, lift it, fill underneath, put the turf back. That way you're not burying grass.