When deciding to join any martial arts organisation, you should first look to find out who your instructor trains with and the governing affiliations they are accredited by.
Throughout the Martial Arts industry, there are unfortunately some unaccredited instructors, alot of which may win a few tournaments or train a short time and then claim they are qualified coaches and trainers. By training with such people, you are not only at higher risk of the development of bad techniques/habits but you also at higher risk of being injured and mentally scarred.
Many organisations may claim to be "Internationally Affiliated" with a larger organisation of their style eg. for Hapkido, The Korea Hapkido Federation. Verify this by asking to view their certifications. Ensure to contact the governing organisation to verify the school's membership, use an interpreter if need be.