For cleaning after cooking, you shouldn't turn up the gas, close the top, and walk away. Instead, run the burners on high for only 5 minutes—set a timer—before turning them off.
Then scrub the grates with a grill brush or a ball of foil pinched between tongs. If you don't feel like cleaning right away, try this next-day trick: Fill a spray bottle with equal parts vinegar
and water, coat the interior of the grill, close it, and let it sit for an hour. This softens residue for your brush without the need for heat.