Did you already apply for membership and have it declined? If so, were you given a reason? If you haven't already applied or were declined without a reason given, for the most accurate advice, I'd inquire with P411 directly, so they can advise you on what exactly it is you need to work on (ex. more reviews, reviews by more established reviewers, a personal vouch, etc.). Or it could be that your application was just missing some info -- phone number or email address or something. Regardless, I'd just check with them and see what they need. They're very friendly and easy to work with.