My biggest mistakes:
1) I bought 1 BTC for 3000$ at June and after 1 weeks bought for it a bag of altcoins which are folling down up to November 2017, but actually I fixed profit or zero at USd, but not at BTC
2) I didn't take part at one very good bounty project, where my friend recomended me very long time. He made totally 20.000$ and I was shocked and went drink wicky.
3) NXt also bought on the high and now -90%. Such as examples a lot. Some examples very good, bought XPR for 0.3$ sold for 3$