To dream of writing is an attempt to communicate information that we have.
Sometimes the instrument we are writing with is important.
For instance, a pencil would suggest that the information is less permanent than with a pen. Our signature in a dream suggests that we have an appreciation of ourselves. We are prepared to recognize who we are and to make our mark in the world.
Also consult the entries for ink, paper / parchment and pen / pencil for further information.