Whether you're looking to hire a trainer/coach for the first time, or you've been with someone for a while, there's one question you should put to them - sooner, rather than later:
Who's YOUR coach?
Before I go any further, I think it's important to distinguish between "hiring a coach" and "trading sessions" - the latter being something that's pretty common in our industry. Trading sessions are still a valuable resource, because they allow for a little bit of extra energy to be injected into a session, gives trainers an opportunity to see what else is out there, and allows them to pick up a new trick or two. However, when I say that trainers need a coach, that is not the scenario I'm talking about. What I mean is that they should hire (in other words - pay) someone to design a program and coach them - teaching them new skills, as well as helping them to practice and refine their current ones.
You see, a few years ago Sasha and I had decided to take part in a two week business-development program (fitness specific) and one of the first questions from the teacher was "Which of you has a trainer?" - to which the reply was generally "Not me". He then asked why, and the usual reasons were given - "not enough time", "not enough money", "I can do it myself"... but he silenced all of us when he followed up with "If you don't see the value in the investment, how can you ask somebody else to invest in the exact same thing with your business?"
Further to this, I also believe it says something about the coach in general. It suggests that they are open to learning, that they have the humility to recognize they still have things to learn, and that they truly believe in what they're asking you to buy into. It also means that they understand things from a student's point of view - the challenges and obstacles that are faced, ways to overcome them - all of which are experiences that will be invaluable to you as their client/athlete/student.
So the next time you see your trainer, or are shopping around for one, be sure to ask them who is their coach... and if they say don't have one, put them on the spot and ask them why.