Buy altcoins at low price and sell at high price
But finding the right altcoin is hard and it's never a good idea to put all your money on 1 investment. If i were him i would invest most of it in bitcoin and keep the rest for some altcoin trading. Never considered mining because i dont have any knowledge about mining so i won't talk about that.
Investing in bitcoin and different altcoins is the right thing to do as price of bitcoin will surely go higher in future and altcoins can take care of short term profits which will eventually also help in increasing the number of bitcoins in your wallet.