Doesn't matter how many currencies there are disponible on this market, you should always go for bitcoin first. The highest percentage of a crypto portfolio should be concetrated in bitcoin and only a small percentage like 5% or 10% should be invested in altcoins. As a newbie, your friend must know how to create an account in a legit and safe platform where he can buy or invest his purchased coins. Then he can create his BTC wallet address and start managing his funds. It's also a must to set security configurations on his account properly, to prevent being hacked and losing funds.

As the time goes on, your friend becomes more experienced and profit is made, he can invest in a cold/paper wallet to store his cryptocurrencies offline, what is safer than storing coins at an online platform, although it won't generate any passive income over his money.