I'll give you a sincere tip, something that has worked for me. Don't buy coins that are already high. The right time to buy is before the coin takes off. Now, it can continue to rise for a few minutes, maybe even a few hours, but soon the mean reversion effect should bring the price down. The ideal is to look for coins that are low, but that have good fundamentals and a solid history. A riskier strategy, but one that has brought me good results, is to invest in smaller coins during a phase of high volatility, when they are among the biggest declines. High volatility and the tendency to reversion to the mean will make them rise again. But remember, be patient and don't sell at a loss.