Knowing how to use a skill is not the same as knowing how to teach it.
A good teacher can tell you which exercise would provide you deliberate practice at improving on the skill that you want to learn.
A good teacher can point of mistakes that you are making. He can distinguish between mistakes that you can do something about and mistakes that aren't woth your attention because you can't fix the issue at your level.
A good teacher can tell you if a change that you made improved your technique. Positive feedback is important to keep the chance instead of going back to what you did beforehand.
How do you become a good teacher? You teach people and see when you teach successfully and when your teaching is crap.