I recommend for Composers to join American Guild of Organists

This recommendation seems unusual but you can learn much from the certification guidelines for the various levels. If a non-keyboard player, the musicianship, improvisation and theory tests are illuminating and at the highest level quite challenging.

I have been yearning to go for the Colleague Certification but it is a matter of money and time to prepare the rep and get training in improvisation.

For those who are in junior high, these exams offer a good reason to study piano/organ as the certification programs offer a great way to prepare for college and grad studies.

Here is a link to their exam requirements

http://www.agohq.org/docs/pdf/ProfCertRequirements.pdf