Getting feedback is the most important thing in knowing yourself. It is because when you get feedback you see yourself with different set of eyes. You start to focus on what you never thought of that you have in you.
But it also important that when getting feedback you should include only those that are really close to you. The person how know you and understand you.
You can always seek help of a professional. You can seek profession help when you want to get feedback about some specific field. Lets say for example you want to became a better pubic speaker so you should get a feed back from a person who is already good in it. And give coaching.
These are some things that you can do to learn more about yourself. Learning about yourself is a on going process and you keep learning as you grow and develop. So have an open mind.