Sweep out the entire garage floor. Mix garage floor cleaner compound with water according to the manufacturer's directions. Scrub the garage floor with the cleaner and a stiff bristle broom. Hose out the garage and allow the floor to air dry completely.
Mix the correct amount of non-slip paint additive to a gallon of floor paint. Follow the package directions for the specific amount of additive required for each gallon. Stir the mixture thoroughly with a wooden paint stick.
Coat the entire floor of the garage with the textured paint, beginning with a back corner and working diagonally toward the opposite outside corner. Allow the paint to dry completely.