1) Making decisions from blind panic rather than cold logic. This is panic-selling as well as buying through FOMO. You should never ever buy or sell just because a coin is rising or falling in price. You need to understand why its price is moving.

2) Not setting an exit point. If a coin starts to rise, it is very easy to hold on too long, and only sell once the price has dropped back. The problem here is that price drops are often quite harsh, so the best time to sell, counterintuitively, is whilst it is still rising. It is important to set yourself a target exit point in advance.

3) Not setting an entry point. This is also important. If you decide you want to buy a coin, you need to assess its current price, and whether this is likely to fall to give you a better buy-in point.