The best way to know which currencies to invest is to read about them and to study those that arouse their interest.
Once you do that, you're likely to learn that you should avoid investing in an altcoin based on the bombo created around it.
Many coins are known to use pumping and unloading schemes. The creator of a certain altcoin generates rumors about the altcoin for people to invest in it, inflating the price of the altcoin. Once the price of the altcoin is appreciated, its creators will sell everything, leaving most investors with useless currencies and without anyone to sell them to.