Have an Answer?
The answer to this will depend on the level/degree you are pursuing, and have completed. Are you seeking a specific type of population (youth? adults? older adults?, etc.) or demographic (gender-specific? geographic location? etc.) in your preferred experience? Or, are you just generally interested in any opportunity where you can directly work with mental health clients?
The company I currently work for, offers different types of internship opportunities, so I can provide more detailed answers, if you are open to letting me know whether you are a graduate student or if you are seeking a bachelor's level of internship before getting into grad school.