1) As this is a website clique you are required to have a website if you wish to join. Your site can be about anything, although social networking sites such as twitter and facebook are not accepted. Sites such as Livejournal and Deviant Art are acceptable.
2) You should link back somewhere on your site. Although I won't make a point of reinforcing this rule (I don't have the time :P), linking back comes with the benefit of securing your claim even if your site is not updated.
3) If a book/series is taken you may not claim it. The only exception is if their site is dead or inactive (and they're not linking back). If this applies you MUST make a note of the member's name on the comment field of your application form.
4) It is first come, first served for claims.
5) Direct linking of any image on their site is strictly prohibited and will result in your membership being rejected.