As a newbie, I have little experience in choosing a promising altcoin and there must be some important thing that I don't know now in the process of choosing a altcoin. I want to stand on the shoulders of giants and I hope you can teach me something. Thank you.
There is nothing special about Altcoins. You can do your research on the coin. Google the alt coin, watch reviews from other investors and read as much as you can. Always join projects that you understand.