If you have a metal tray, you should first wipe the surface with a dry paper towel to remove heavier debris. Then spray it with vinegar or mild household cleaner, leave it for 10-15 minutes, wipe it with a clean cloth and rinse the cleaning solution off in the sink. Dry it with a cloth or paper towel removing any beads of water to avoid rusting. For plastic and wooden trays, fill the sink with soapy water, leave the tray to soak for 15 minutes, scrub gently then pat down and air dry.