The general rule with carbon steel is to keep it clean and dry. Basically, when you are done using the knife, clean it off with soap and water. Make sure there are no food particles left anywhere on the knife. I use a double-sided sponge with a more coarse side if food is dried and stuck on. Then simply dry with a paper towel or rag. Apply a light coat of mineral or cutting board oil to the entire knife at least once a month. This will protect the handle from drying out and the blade from rust. The blade will develop a natural patina with use that will help protect it further. Different foods will change the look of the blade as this happens. It is completely normal and will add to the personal aesthetic of the knife. NEVER IN THE DISHWASHER!! Keep honed with a rod regularly and when needed, sharpen with a flat stone at about a 10-15 degree angle.