Paul,  I have been a tuner/technician since the late 1960s.  I can
recommend the PTG (Piano Technician Guild).  Find a chapter near you
and go to the meetings.  There is a web site for the PTG.

You should realize some technical skills are needed.  Note the article
in MMD 01.07.16 on a tuner leaving a customer with his instrument not
working.

Learning to tune will take many hours of practice. It is well worth it!
Each instrument has its own special character.

Hope this helps, good luck,

Donald Dusenbury