Wash your cutting board with soap and warm water and scrub well. Dry immediately with a towel and let it air dry standing up or on a raised rack with air flow.
Wait until the board is dry, then apply a small amount of conditioner onto the board. Using a soft cloth, buff the conditioner into the wood in a circular pattern, forming a thin coat. Repeat over the entire surface of the board and especially the sides. You can also use a cutting board oil or conditioner food grade from any hardware store.
Do not put the board in the dishwasher. Will warp and splinter the wood.
Do not dunk or let the board in stand in water. Will absorb water and potentially warp.
Do not use bleach. This will stain the wood.
Do not put a wet board flat to dry. If the board dries on one side, it will cause the wood to warp.