If you used an extra blade feature (such as for julienning), return it to its original hidden position. If your main blade is adjustable, set it to its lowest position. Wipe slowly from the base of the blade to the tip, to reduce the chance of cutting yourself. Once any food scraps or stains are gone, rinse off the soap under running water. Put it on the rack to air dry, or dry it carefully with a towel. Storing the mandoline while wet can lead to rust. Mandolines are significantly more dangerous than knives. Never leave them somewhere a child could reach. Ideally, keep your mandoline in a labeled container. Never place it loose in a drawer or on a high shelf where someone might put their hand without looking. An occasional deep clean is a good idea if you use your mandoline often. Most plastic mandolines and some stainless steel mandolines can be run through the dishwasher, but hand washing is gentler on the blades. When washing by hand, handle with caution and consider wearing cut-resistant gloves.

Summary:
Adjust all blades for maximum safety. Wipe the blade with a wet, soapy cloth. Dry thoroughly. Store away from children and pets. Give it a thorough clean when necessary.