Anyone age 18 and older who is mentally competent can write a last will and testament in Washington state. Writing a will does not require the help of a lawyer, but it must follow certain formalities. The basic rules are that the writer (“testatator”) must intend for the document to become a will, the testator must sign it, and at least two adult witnesses not mentioned in the will must sign it.
Display your mental clarity and understanding of what you are doing with clear language such as "I, (your name), on (the date), in (your city), do hereby bequeath my property as follows." Then specify who gets what.
Sign the will. Some states do not require the writer's signature if the material portions are handwritten, but Washington state does require a signature. The signature need not be the testator’s full legal name; an informal name or initials suffice. If the testator is physically unable to sign the will, someone else may validly sign for him in his presence at his direction. In that situation, the other person should write at the end of the will that he signed his name at the testator’s request and then sign his own full name.
Ask at least two witnesses to sign the will immediately. They must also be at least 18 years old and mentally competent. The witnesses must know that it is the testator’s will, and they must sign their names while in the testator’s presence. It is enough to tell them, "This is my will. This is my signature. Please sign your name here."
Store the will in a safe place. Defaced pages usually will be interpreted as a revocation of the will, so do not tear, cut, mark, burn or otherwise deface any part of it, however small.