After making several major mistakes in the past I realized that buying cheap coins and holding them is best idea.
I missed to buy ether because of all "warnings" how ethereum is bad. I had more or less 100 dash when its price was 4$. I had lots litecoin which I have sold for - 10$. I had lots altcoins in january 2016. and I've sold them all. I sold my bitcoins for 500$. Last year I sold them for 2400$.
I regret all my past decisions.