Mistake I’ve frequently made is participating in too many markets at one time, which leads to sloppy trading.
I’ve also found that it’s my smallest positions that cause my biggest losses, because they tend to be neglected. It’s natural to be cautious and attentive to big positions. With the small positions, it’s easy to fall into the trap of being complacent. My awareness of this pitfall has made me more careful with such positions.
I realize that I’m only human, and that I’ll always make mistakes. I just try to make them less frequently, recognize them faster, and correct them immediately!