When making an introduction, you obviously don't want to:
Give out any personal information, such as telephone numbers, addresses, etc. If you do, one of the admins/mods will delete your post [and it won't be in the Archives, either!]
Send out personal photographs along with a post.
Spam by commercializing a site or product.
What you can do though, is use some tips!:
State your name, or what other users can call you.
What are you "in" to? Music, art, reading... anything!
What are some of your hobbies?
[Stating your age/displaying a photograph of yourself is totally up to you]