Currently the only way to join Tango Evolution is to request membership from one of our current members. That member can then nominate you for membership and as long as a majority of the other members agree you will be a member.
However, the main thing to know is that there are NO benefits to being a member. On the contrary, there are only responsibilities such as helping setup and break down milongas, etc.
We are looking into creating a basic membership which will include a membership fee and a discount on milongas, classes and workshops. If you would be interested in this please email firstname.lastname@example.org so that I can judge the interest in this.