Self Awareness:  They know their personality and how they are hardwired as a person. They then develop a trading style that is in-line with their personality.

Know your edge:  They know what their ideal set-up looks like. They trade only when they have an edge and they vary the size of their trades based on how much edge they have: Big Edge = Big Trade; Small Edge= Small Trade; No Edge = No Trade.

Accountability:  They keep a daily trading journal so they can review what they are doing well/poorly, game plans, trade sizes, etc.