In short, buy when prices are low and sell when prices are high. but we need to pay attention again so that we are not greedy by continuing to increase the estimated profit that has been set previously because we are afraid that the price of the coin may just fall. as a result we will experience a loss of time because we have to wait for the market to rise again. It's also important for us to often monitor market developments so that we can always update coins that have good market prices.