Yes, Buy low, sell high that was also my number one advice. Here is what happened:

• When I started trading, sometimes I didn't zoom the graph out to one year, or 'all time'. I thought I bought low, but when zooming out I discovered I bought nearly on top.
• Sometimes I got emotional, was pretty sure that the price would go up. I bought it on top, but Bitcoin suddenly went down. (that was the news that China banned ICO's).