I don't think anyone would be foolish enough to let someone do brain surgery on them merely because the other person is interested in brain. No matter how persuasive that person is, you would like not give them a chance to practice on you.
When clients come to you for help, they want to know that you have knowledge, skills and abilities that are backed with both training and experience. They also want to know that they can be confident you will not harm them but instead meet accepted standards of practice for your field.
It is your responsibility to ensure that you know those standards of practice and follow them. If you are unsure or don't feel confident in a specific area, you can improve through various means including self-study, completing courses or workshops, setting up mentee arrangements or doing internships.
Unconscious incompetence means that you don't know what you don't know. We all have blind spots that can jeopardize our personal and professional lives. Because of these, it is important that we have honest peers who will not only point out our flaws but also help us to figure out how to overcome them.
Knowing standards of practice and developing your expertise will provide many benefits for you and your clients. Everyone will have more confidence and be able to trust that clients will receive good ethical services to help them with their problem.