I have a limited knowledge about trading cause i'm still in the process of learning, what i have learned in trading is the usual, when the price of the coin is decreasing should you buy it then hold it until the price of the coin that you bought increases, sell it. Trading is a risky way to earn btc or altcoin, You should have the knowledge of the basic principle in trading and must familiarize the exchange platform you'll use in the future. There are this lines and curves that are being used in the exchange platform to know whether the price of the coin is going down or going up, you should familiarize that too and make it as a guide to your trading.