In the Japanese mindset there are certain errors that are required for understanding. There is no judgement attached to the making of those errors, because if you do not make them at some point then you cannot eventually master the subject at hand. In martial arts we run into much the same phenomena: I have to understand on a visceral level how to move my body, and to do that I have to train my body and make a huge number of mistakes.
No matter how well I think I understand something, it is best to show humility on the subject in the presence of both those with less experience and with more. Those who I think have less experience may still surprise me with a new insight, those who I think have more experience--even if I disagree with them in some fundamental ways--may be able to point out things that will lead me to new realizations, or help me improve myself. If I believe that I am knowledgeable about a subject, chances are good that I am very very wrong.
This means more than not "comparing dick sizes with Odin" (though that is also important). It means laying ourselves before our gods, before the universe, before others, and before ourselves and recognizing the fundamental truth that we know very little. The more that we learn, it should be the more we realize we don't know not just about the universe, but about the very assumptions that led us to this point.
Magical practices--especially shamanic practices--are often difficult to keep in perspective. The force of Will needed often requires an extremely firm belief, because doubt makes it very difficult to get anything to work, much less work safely. It also becomes a challenge, when we believe we talk to the gods and spirits, to remember that we are--at best--an imperfect receiver for Their messages, and that in many respects even They are not perfect. My instructor in martial arts is an 8 dan in Tae Kwon Do and an 8 dan in Hapkido, but if something doesn't look or feel right it is my responsibility to recognize it and try to understand why (this doesn't mean "contradict the instructor in class," but it can mean "be sure to ask for reasoning, even if the answer is going to be of the form 'because the fence needs to be painted'").
Yet for us, as Occultists and Spirit Workers, this is even more important than it would be otherwise simply because it is so difficult. If we pretend to authority, capability, or powers we do not have, then we serve no one: not our clients, not the gods, and not ourselves. If we believe we know more than we do--if we believe ourselves as knowledgeable--then we approach the world with preconceptions. These preconceptions then block further development. As we say in my martial arts class: "Disregarding criticism because of pride in knowledge is a sign of ignorance."
Of course, I can hear the complaint now "Humility is not a Norse virtue." This is basically true, but as it is said: If there is one person in all of the Nine Worlds you cannot afford to lie to, it is yourself (Loki's lesson). You cannot--as an occultist--tell yourself that you know more than you do, for as Dion Fortune indicates in the Mystical Qabalah, above the gates of the Mysteries are written the words "Know thyself." What you show others isn't nearly as important as what you tell yourself.
I can be justifiably proud in my progress while at the same time recognizing that my progress amounts to less than a single grain of sand's worth of knowledge on a vast shore. Showing humility doesn't mean that I must grovel and debase myself for the sake of debasing myself, but it does mean that I should not flatter myself as being stronger than I actually I am.
This is, after all, about my own personal development and growing both as a person and as an occultist. Not about showing off.