Hold during a bull market. If you sell, you might lose your position where you may never regain again. Like Bitcoin at $1000 in the beginning of 2017. Now, in a bear market if your able to sell early, you may be able to let the market correct far enough so you can pick a new position at a much cheaper price. If you try to sell too late at near bottom prices, then you might also lose your opportunity so it's better to Hodl. It all comes with experience so practice now.