When we are going to get involved for the first time with the crypts, we usually have doubts by ignorance and we feel overwhelmed by being inexperienced in this complex crypt.
Hence beginners should not jump into investing or trading. They should spend more time understanding how to secure their wallet and devices because that is the biggest hole they already have and is correctable. Learn about phishing and scams and how to avoid those and then start thinking about which coin to buy.
Which project crypt considers that it is the best for beginners? Especially in terms of ease of processes, security and features that facilitate accessibility.
Although you ask about altcoin, I will suggest you Bitcoin. Reason is simple, bitcoin is the only coin that has censorship-resistance and decentralization. It may not be completely anonymous but you can work around that without breaking a sweat unless you are looking for laundering money.
But like I said, securing your system is more important first. Learn about the bitcoin network works and how the price of bitcoin moves and news of the world have been influencing the price. Then only you will be able to choose the correct point to buy or sell. Do this from reading price charts on any site of your choice.