I get asked that question often and I always give the same answer: "I would have asked for advice more often." I made a lot of dumb-ass decisions by not taking the time and running it by my mentors and sponsors first. I don't know whether it was pride, hubris or impatience that caused me not to do so. Fortunately, I was able to overcome the decisions and have a very successful career. So, if you are faced with a big decision, even if you think you know the answer, run it by someone more senior before deciding. If you don't, you run the risk of your decision being a dumb-ass one.