Wonderful tips! It really does boil down to emotion. Humans are irrational and as such, we do things that are quite ridiculous during the heat of the moment. It's forgivable, as they say "we're only human" but it does incur losses.
Apart from "buy low, sell high" what I've done recently is I've kept a personal ledger of what price I bought it at and the current price so that I could see the profits I have made and assess from there if I want to part with it. I got the idea from @lukestokes, and at first it felt a bit tedious seeing as I only had a few coins, but as my port grew so did its usefulness.
Here's a link to the original ledger which you can make a copy of: https://docs.google.com/spreadsheets/d/16PJwy8i3rlyEtQedaTFpk0lR6SaLvelfo90x5oM4aro/edit
It already has the formulas set up, so it's basically plug and play. I hope your other readers find some use for it as well, my friend.