Leaf mulch can help keep soil cooler in summer. Chopping or shredding the leaves first will help prevent them from matting down and preventing air from reaching roots. Directly applying the leaves to a garden or unused area of soil is another option. Try to spread the leaves over as large an area as possible, then till or plow them under. Chopping or shredding the leaves first will help them to break down faster.
Dry leaves are much easier to handle through the mower than moist ones.
If possible, remove the bagger so all of the leaves are deposited right back onto the lawn as they shred.