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.
Finding an investment is always hard, may it be an altcoins or not, that needs a effort and careful study of what you are planning to invest. Right now, the best investment in crypto world in terms of long term is Bitcoin, we have seen how it grow and it will surely continue to grow. Different investment requires different approach, you are good to go with altcoins if and only you have time to monitor how the price move and make money for short term trades than long term.