Theres always a risk in this methods that you share, I would not recommend investing in ICOs because most of them turns out to be scam or negative ROI. Trading, if you know technical analysis then it is one of the best way. Hold, will take you long time probably 2-3 years. But the most famous right now is staking or running a masternode. In this way, your altcoins will grow in time but be careful in picking the right altcoin.