In concept nothing could be easier, you just decide it is for you, there is no subscription, membership fee and we have also discontinued the central register. The president would like to know that you have become a citizen, and to do this use the form you can get to by clicking here. Contacting the president is completely optional; and you can become a citizen without telling anyone at all.
Some like to have a ceremonial element and this is often provided by one of the trusts they join. If you create your own group then of course you can create your own ceremonial, but it should follow the concept of a commitment from people and them being honored for giving the undertaking. You should take great care not to involve anything that can be misunderstood through ignorance, stupidity or by those having some other motive.