After learning the first, it is important to learn the second else you will be a trader with a strategy that should work, but no profit to show for it. When you hear of traders who were successfully able flip small account sizes to big ones in a short time, it is not just because of their strategy alone, it is also due to understanding of how to maximize profits and minimize loss.
What's far more important is being able to manage trading behavior. I mean, You know when to stop after taking profits. Greed disguised as a desire to maximize your strategy can lead to disaster. Remember, you can't control market volatility, but you must control trading mentality. Many traders fail not because of a flawed strategy, but because they start to get emotional.