Selling coins effectively is a way, determining which coins have good potential in the future is bought and sold.
Maybe it will be difficult, especially when there are so many coins in the market Cryptocurrency.
Do trading carefully and use a good strategy.
Perform price monitoring always on the coin market cap.
If the coin price drops and has good potential then you can buy the coin and sell it when the coin price has gone up, so you will get a bigger profit.