In short dont be greedy.
If we see a growth to our coins that we hold and made profit be contented to it.
Dont aim for high return unless if you're certain that this particular coin can give you the profit you really want.
Greed and wrong decisions are linear in nature. After seeing what happen to Yam finance bug that plunge the price from $130 to almost $0, I will never hold alts for long time. Investing in cryptocurrency in risky but marring Alt coins will be suicide.
The best way is to diversify portfolio, %20 interest is okay for me to move on to the next hot project.