Sweep off your deck with a broom and dustpan.
Combine one part trisodium phosphate, commonly called TSP, with three parts water in a bucket using a hose.
Clean your deck with the mixture using a scrub brush. Rinse it off with the hose and allow to air dry.
Attach fine-grit sandpaper to an orbital sander. Run the sander across your deck to remove any splinters.
Sweep the deck again with a broom and dustpan.
Unpack non-skid strips from the packaging. Lay it across the deck along the center line of each plank.
Cut the strips to fit the length of the planks using scissors.
Pull the backing off the strips one by one from the edge of the deck toward the house. Use a roller to press each strip to each individual plank.
Allow the adhesive to bond to the deck according to manufacturer directions before walking on the deck.