Understand principles of energy. This is the most important thing.
There is only one principle, motion, which has two phases, yin and yang. These define the direction in which energy is moving. Yin energy decreases. Yang energy increases. This is all you need to know.
Do not waste time thinking in terms of duality. Direction is the key.
Apply this to fighting, your opponent cannot fool you. His intentions are clear to see.
Apply this to life and who knows what can be achieved!