Common mistakes

Marketwatch has an article "The 7 biggest mistakes fund investors make" (link). Some of them apply directly to traders, some not so much.

1. Chasing returns
2. Rear-view investing
3. Overreliance on rankings and ratings
4. Assuming you can buy and hold a fund forever
5. Failing to understand what the fund does, how it invests or what it buys
6. Letting emotions rule
7. Focus too much on a fund, and not enough on the portfolio

For traders, 1, 2, 3, 6, apply directly. Another might be focusing too much on picking winning trades, and not enough on risk management and right sizing of positions. Number 4, doesn't apply direct, but perhaps for trading, thinking that a single indicator will always keep working.