Yes obcourse buy low and sell high is the golden rule in trading and in the way you can earn a good profit but not only that you can also learn more about crypto. When you doing trading you need to learn to control your emotions too to avoid loses.
I am a long term trader and choose to stay in the market as long as possible. This thing has two advantages. One it is the only way to maximize the profit after investing in the coins at low price. Bought in bulk will earn huge per unit profit. Besides, I stay patient and consistent in times when the values declines. This is the time I hold my coins because if I sell them, the money I had planned to earn will simply not be there.