Neil, if you're feeling adventurous you can do the ideal surface prep...wash, dry, use a clay bar and then do a final wipe with isopropyl alcohol before applying the Turtle wax coating...or you can just do a wash and dry and apply the Turtle Wax, it will still look great!! Spray on, wipe off!
(last night I decided to clean my helmet for the first time this season..and I used the Turtle Wax on helmet and visor after cleaning. Helps keep it cleaner and easier to remove bugs)