Here are some rules that have to be respected.
1. You need to give a name/nickname, email, url, and claimed charcter
2. When claiming the character, first check the claimed characters because it works with first came first served, the same character won't be given twice: Sakura Kinamoto and Sakura from Tsubasa ARE NOT THE SAME CHARACTER - same goes for Tsubasa Reservoir Characters (doesn't apply if the character apears twice in TRC) TRC Kamui is not the same as X Kamui, but X Seishiro is the same as Tokyo Babilon Seishiro.
3. You can change the claim whenever you want, but you can't choose a claimed character.
4. The code must be on your site as soon as possible, personaly I normaly put first the code and then join.
5. Any site is welcome; just keep in mind that I won't list hating/porn sites.