Can someone who is not licensed cut hair in the state of Washington? Is it okay if the customer is warned beforehand that the person isn't licensed?

My understanding is, at least in my state, anybody can cut hair but if you do not have a license you can not set a price to charge. If you are licensed and do not operate a hair business but cut hair for extra money you still are not allowed to charge any set price but have to accept on a ''donation'' basis.
I think it is only right for a person to be warned they are not licensed. They may want to make up a portfolio so people can see how they do.