Annual dryer maintenance involves the following 5 tasks:

Clean lint build-up from vent system. Out of the back of your dryer you'll find a pipe, usually 4-5 inches in diameter, which goes through the wall of your house to the outside. Outside there is a "flap vent" that swings open automatically from air pressure when the dryer is running, then closes when the dryer shuts off. The entire piping and flap vent should be inspected and cleaned of lint or any obstructions.

Seal any hose joints with duct tape.

Clean behind and underneath dryer. Moisture, dirt, and lint tend to accumulate behind and underneath your dryer. Pull the dryer out from the wall and wipe these areas with a damp rag.

Scrub the lint trap. Chemical fabric softeners often clog the small holes in lint traps.

Remove the lint trap and scrub it with a soft bristle brush and mild soap or detergent.

Check the balance of your dryer. A dryer that is not level on the ground will cause its' rotating components to wear out sooner. If the dryer moves, shakes, or is not level, adjust the feet at the bottom of the unit.

Clean and inspect burner (gas models). For dryers that heat with natural gas or propane, the burner should be cleaned and inspected according to the manufacturer's recommendations.