When trading there are rules to observe in other to protect your margin, it's more like if you can't make more money, don't lose the one you have,
That's my rule from the last 3 years, as one of my teachers (well he was a chemistry teacher) teach us this rule that, if you are not making money then stop wasting it also comes in the same category of earning it. So from then, i always try not to waste money on useless (unnecessary things). So, yes i totally agree with you that, stopping wasting money is better than not earning.
_ Don't risk too much money, start with what you can afford to risk. Focus on the risk not rewards.
I don't think, its a good idea to focus on the risk, not the rewards, because the reward is the main purpose of your trade, and if you will not focus on the reward then how can you use Stop loss which you just mentioned below this point. Because in order to put stop loss, you must have a reward (profit) in your mind that you think you could get according to your analysis. And sometimes, stop loss comes in handy when the market takes unpredictable turns, like a recent one when Binance get sued by SEC.