Wikipedia Guestbooks, according to Wikipedia founder Jimbo Wales, "can help build a spirit of friendliness and co-operation, and help people get to know each other as human beings". All Wikipedia users are welcome to create a guestbook and give permission to other users to sign it. However, creating a guestbook is also a privilege; many users have been blocked just due to begging for someone to sign their guestbook.
Guestbook cautions
Do not beg others to sign your guestbook. Users eventually will come to see your user page, and many will click your guestbook and sign it without being asked.
Never ask a user to sign your guestbook by posting that message on a talk page.
Be patient. Users will eventually come. After all, you should not be here only to see who signed your guestbook...