You have to understand the market trend. Some make money when the market falls (short selling) and major do when it rises. It might not be easy at first but with a proper watch, you will get the market trends. Learn from the history. 2018 is almost similar to how cryptos behaved back in 2017. Learn some good trading strategies. There are exchanges with many order- stop loss, stop limit to save from losses. So you do the profit and loss analysis and make strategies that can generate profits. Hold if needed or trade. It will come naturally. But keep learning.