Position size: the rule that keeps you alive

Your order flow reading decides where and when you enter. Your position size decides whether you will still be here in six months. An average trader with strict risk management survives and improves; an excellent reader who trades too big always ends up meeting the losing streak that empties the account. This lesson is the most boring of the course, and the most important.

The principle fits in one sentence: you first set how much you accept to lose on a trade, then you derive the number of contracts from the distance to the stop. Never the other way around.