NATS is a great organization. Members receive the monthly Journal of Singing, which contains abundant articles on everything to do with singing (interviews with famous singers, scientific research, examinations of pedagogy, articles from current members, reviews of new music and recordings, etc.) The national organization sponsors national competitions, offers different types of grants and awards, master classes and events, NATS chats, posts job listings, teacher directories, etc. Take a look at www.nats.org .
Joining the local NATS is necessary to submit your students into the NATS auditions. Check out www.mddcnats.org to find out about our local chapter. Besides student auditions, we also sponsor two workshops each year (past topics have included Ornamentation, Teaching the Male Voice, Musical Theatre Technique and Auditioning, Vocal Health, etc.) Other organizations for singing teachers are the NYSTA (New York Singing Teachers Assocation www.nyst.org ), MTNA (Music Teachers National Organization www.mtna.org ), and ACDA (American Choral Directors Assocation www.acda.org ) among others.
A great resource for singers is www.auditionsplus.com by Classical Singer Magazine. Check it out!
Recommended exercise books:
Marchesi, a Theoretical and Practical Vocal Method
Marchesi Vocal Method Opus 31
Lamperti Daily Exercises in Singing,
Panofka 24 Vocalises, and Mozart Solfeggi (only for very advanced singers!).
Listen to this clip of Edita Gruberova singing the Bell Song from Lakme to hear an incredibly perfect vocal technique!
Here is a very interesting article in The New York Times about the state of voice teaching today in the US. I agree with everything in the article and have been saying for years that studying with a teacher once a week is just not enough!