The most important thing in crypto invest is diversification. All in to just one coin is very risky because of all these volatilities. Spread your money to some coins that you think have good progress is better than putting all your investment in one coin. It prevent you from a big lose.
I agree, diversification is a safer way to spread investment but we must make sure that we can follow each investment because too much of diversification to the point of failing to follow each investment will cost us more harm than good.
As of the coins, you can check the CMC for the one that yet to get pumped but with an active developers that keep on updating even though they had a low volume, low priced market. This is the best one to pick since there is a huge possibility, as long as the developer keep on communicating and delivering the roadmap, that it will get noticed and get hot one day.