You have to avoid buying at the top as the price pump it could be very risky to buy because that is when the price was about to retrace or reverse, thus it is mandatory to have some basic skills on price chart which would help you to determine the most appropriate period to buy and sell it is always advisable to buy low and sell high, basically I would always advise you to wait for a retracement or reversal in an uptrend price movement ( (bullish) this would ensure that your entry into market is at appropriate price, once the price retraces you should adopt DCA method to start buying and accumulating your choice of coins.