What realistic annual % return you expect? What kind of annual max drawdown you willing to take to accept that return? How much you willing to risk on a particular trade? The above are ideal situations, but in reality a risk can run further if you tolerate a losing position longer than you should. 15% expected gain balanced with 15% annual drawdown for a 1:1 ratio would not be too great. Ideally 30% expected gain vs. 15% max drawdown balanced with 5% max risk per trade, imo. However, very few people can consistently make 30%/yr for many years.