You should look into and study markets in general before investing as everything essentially has risk associated with it. The crypto market is one of the highest risk markets out there with large swings up and down. They are a virtual currency so they have no earnings, just move based on peoples sentiment and technical movement based on the charts.

So you should look into some technical analysis which is studying the price movement of the asset on a chart. (Tradingview has good charts for cryptos)  If you go long, you do not want to purchase when the price is declining as it can continue to drop further and you will lose money. So people wait for an uptrend before they purchase,,,,this is easier said than done and takes some charting analysis.

There are a lot of good books on technical analysis, check some out.