Choose a Healer like you would any other professional.  

Ask them about how they work and what their skill sets are.

Do they have testimonials that indicate their success as a Healer?

Are you comfortable with that person, after all, they will be in your subtle field?

Be sure your healer can explain in a language you understand what is going on.

Can they explain what is going on with you?

You must trust your Healer.