People often debate whether it matters more to win often or to win big when you win. The answer is that both matter at once, and there is a simple formula to combine them.
What the risk/reward ratio is
It is the distance to the target divided by the distance to the stop. If you enter at 1.0850, your stop is at 1.0820 (30 pips) and your target at 1.0910 (60 pips), the ratio is 1:2: you would win twice what you risk.
The break-even win rate
To avoid losing money you need to win at least 1 ÷ (1 + ratio). At a 1:1 ratio you need 50%; at 1:2, 33.3%; at 1:3, 25%. With a 1:0.5 ratio (winning half of what you risk) you need to win more than 66.7%.
Mathematical expectancy
Expectancy (in R) = win rate × ratio − (1 − win rate). If you win 40% of the time with a 1:2 ratio: 0.4 × 2 − 0.6 = +0.2R per trade. Over 100 trades risking 100 USD each, expected profit would be about 2,000 USD before costs.
If the result is negative, the strategy loses money in the long run even if it has winning streaks.