to choose the right coin to buy is to follow trending news, because it greatly affects the price increase to get more profit, you have to be very careful in choosing good coins, because here you are very it is required to use the brain rather than lust, which only thinks about profit, but also has to think about the impact if you buy the coin.
^ I never trust anyone aside from BTC, this is a good investment because it has less risk compared to altcoin invest6mnet which is not good when it comes to long-term holding, probably for a short-term holding bit we still don't sure about when it comes to time frame. Or splitting your fund into two and allocating a big percentage to BTC and the rest for the top 10 altcoins, I will never gamble my money investing in a new project.
As you can see, the price of altcoins was been followed by BTC.
You can sleep at night very well if you are holding bitcoin than on a bunch of altcoins. The point here is bitcoin is a solid investment, it's the most dominant asset in the market, so the entire market reacts based on the performance of bitcoin, and although volatility is there but bitcoin will always remain profitable for long term investment.