The site brainfodder.org has a neat explanation of the Dunning-Kruger effect:
"When someone begins to explore a new field of knowledge, they’re usually full of enthusiasm, but completely unaware of how much they don’t know or understand yet. They’re confident about their new knowledge and believe that they can make sense of new information quickly.
"On the other hand, if a person continues to obtain in-depth knowledge in the same field, they slowly realise how vast the field actually is. The more they learn, the more they are humbled by how much they don’t know. Hence, real experts are often hesitant about making definitive statements."
Being humble will get you far. So here's a video of Rickson Gracie answering a question from a humble student who, having just started out, wanted to learn the philosophy and tradition of true Gracie jiu-jitsu passed on from Hélio, Rickson's father.