Well if you are considering long-term investment then put BTC on your list as it is already established among all cryptocurrencies.
But if you're a person who prefers altcoin what I would suggest is to do their own research thoroughly on the project they are going to. Read the white paper, double check the website, and also like other assets, what is its purpose or benefits to people and users.
Well, yeah, Bitcoin investment is usually very
profitable for long-term investment, but the majority of altcoins don't generate any good profit despite the investment tenor (either long or short). Although some altcoins, too, do generate profit for a short-term investment, it sometimes too results in losses when someone invests in altcoins and holds them for a long time because most of these altcoins keep dumping time after time until they finally crash.
Natsuu, I did invest in altcoins in the past, and I really did do thorough research on most of the coins I invested in, but yet I did not make a tangible profit from it. So, it's not just about doing research and reading white papers; any altcoin project that wants to fail will fail. From the start, their white paper will be genuine with a perfect road map, but some time they will still fail along the line.
I think one of the reasons why people keep investing in altcoins is because they don't really understand the concept of the cryptocurrency market and they think that there is huge profits I'm altcoin investment. If so there arf still some certain precautions we need to take when we want to invest in the altcoins Marketplace.
One very important precaution to take, which might not really be a precaution but a warning, is that the investor should always remind themselves that the altcoin investment might be profitable or not, so let them only invest what they can afford to lose.