Laura Claycomb's Young Artist Corner has a wealth of great resources (and straight talk) on the process of making the step from student to professional. This site is worth an evening's visit, with a great amount of very, very pertinent information for singers (and collaborative pianists) wishing to embark on their careers.
One short quote, on vocal coaches:
Find coaches you trust. They will be your ears throughout your career. You can never hear what you sound like from the outside, and a coach (or conductor) can tell you if what you think sounds fabulous even carries to the first row! A good coach is someone you feel comfortable with, that you feel improves your singing, interpretation, etc..., and doesn't play mind games with you. A good coach helps you find the interpretation that YOU want to bring forward within the framework of the music - he/she doesn't just say "this is how it's done." Style is a guideline, not a straightjacket. A good coach will tell you in a supportive way that you're not doing something right, or if you're developing bad habits. A good coach will not feel the need to say something just to have something to say. If it's good, he/she will just leave it. A good coach is NOT just a fine pianist, but a fine musician who can tell you about style, language, nuance, and help you learn more about yourself in the meantime.