Water blast the exterior surfaces to remove the peeling paint. You'll want to remove all paint from the surfaces before painting again.
Sweep up the paint chips with a broom, and dispose of them according to your area's regulations.
Rent a deck sander from your local hardware store, and lightly sand the deck's surface. This will ensure optimal appearance of the paint.
Sweep the deck again to remove any sawdust from the sander. It is now ready for a fresh coat of paint.