How would I tie her up? I think she should be on her back, in bed, with wrists tied to the bedposts. Initially, her ankles would be tied to the bedposts too, but eventually her ankles will be set free (for reasons I won't go into). She should be comfortable, and the wrist-ties secure, but not so tight as to cut off circulation to the hands.
Of course, if she confides that she has been naughty, that she has been thinking naughty thoughts about men, or that she likes the idea of punishing a man's junk, then we shall have to move her outdoors, where she will be tied to a stake. She can stand there at attention, with her wrists tied behind the post, and feel what its like to have no way to shield her front with her hands. She knows her breasts protrude as if in offering, and that wearing a skirt leaves her very accessible below the waist. And of course, she wonders what comes next.