If you don't have experience in trading, it is better to invest in bitcoi, ethereum and other well-known promising coins for the long term in your portfolio. However, with a large and obvious increase in price in the future, it is desirable to sell some of these coins and not hold forever, at the opposite buy when they drop significantly. It will not be so risky if you follow this advice and it will bring a great part of the profit to the general growth in the long run.