I assume you mean Lolita and stuff like that, soo I'd check the
EGL section on the Cosplay.Com forums, LJ communities (
EGL,
Lolita Handbook), Lolita Bibles etc. As for buying Lolita dresses,
go brand -- there are countless shops out there that do shoddy work, so it's best to check recommended shop lists. I personally love Angelic Pretty or Baby The Stars Shine Bright, plus Fan Plus Friend (they do free custom sizing! *is cheap*).
For stuff besides EGL, then Soompi maybe. There are a lot of Japanese fashion magazines out there (MINA, NON-NO, Kera etc) too. :3
Hope that helps! ♥