The problem with trying to lay out any regrets is that I would equivocate all over the place. When I was arguably too cautious, I also had the benefit of taking more time to research and hone my thoughts. When I was arguably too bold (less often), I came to a quicker realization who my friends and enemies were. I lied when I felt I had to (more often than not "correctly" towards someone who would have been heavy-handed, particularly when I was younger and still intellectually-fragile), and I've had to undo a lot of values-based "brainwashing" that really got in the way of me accepting and having an appropriate confidence in myself.
The second part of the last sentence is an important one, and it requires a little elaboration to properly explain. While my parents were more or less appropriately firm with my sister and me (albeit sometimes strict at the wrong times), they were passive when it came to what others did or said. If other people apologized for deliberately damaging their property, they accepted it without compensation. If the priest at the church proclaimed that the priesthood is for men only, it took me expressing my disagreement on the car ride home to find out my parents disagreed as well (a sentiment they offered in the most passive voice possible). If an uncle disrespected the property of others (like after someone opened their christmas gift), there was never word about it, never mind any warning about staying away from this same person who threatened his kids and wife with violence on a regular basis (fortunately I had the instincts to stay the hell away from him). All of this can seem innocuous in the moment, but it ultimately instills the value of cowardice, to crawl up into a ball or at most express contrary opinions under hushed whispers. It's dangerous, because instead of developing a respect for reason and open discourse and riding that energy towards accomplishing something, you're worried about being "safe" -- you let monsters walk over you, you seek whatever satisfaction you can on impulse with little regard of the consequences to yourself or others (and given my parents' inconsistency with being "firm," I wasn't about to learn how to act in a more sensible manner), and you avoid taking responsibility when screwing up because you're afraid of taking the heat (even when it would be a simple "teachable moment"). You may be successful in presenting passable appearances, but you're not going to be happy. Mind, I had a wonderful talent with math that helped provide me with a productive escape, but even that could turn me insufferable (and given all the adults who tried pumping me up to irrational levels on that front, I was basically playing to expectations... just like a coward needing solace should).
I've definitely made mistakes that I regret committing, but I feel that most of it comes with the territory of living in that wretched era of my life. I had a lot of things going for me that gave me something to live for, but (mostly) extricating myself from that situation and mentality has made me a lot happier, even as I'm still navigating my detachment from about anything binary.