Sometimes, the most simple and basic ideas can lead to better performance in trading. As we know, trading is a lot about having rules and obeying them. Maybe, when those rules are complex or can be bent, it's more likely that they will be broken. A simple rule has, therefore a good chance of being applied in a very rigid and disciplined way. In this article, I will share a very basic and easy rule that I use and have used for quite some time now. I call it the One-Trade-Per-Day rule. As you can guess from the name, that doesn't sound like a very ingenious idea. And it isn't, but it works.