Positive risk to reward ratio is very important. I find it weird how many traders trade with 1:1 or less when they can do say 5:1 or more. Everyone knows the casino has a very small edge but they end up positive year after year. In fx, you can have all the edge you want.
I mean statistically trading with a positive risk to reward ratio is more likely to affect your profitability then a negative. A coin toss experiment comes to mind.
But yeah it is easier said than done. The truth is trading fx is probably the hardest way to make easy money ever invented.