Part of your selection of any psychology professional should be a thorough examination of his or her credentials. If necessary, ask them directly about their experience, education, and licensing. While this may seem rude, it's important, and it's a step you shouldn't let anyone pressure you to skip.
If you've been diagnosed with a mental ailment, ask your psychology professional where you can turn to learn more about the condition so you can work more closely with them to treat it. In many cases, you can work together to come up with a treatment plan that helps you live normally.