This question could also be read as : As a professional researcher, you wish you would have done some things differently than you did when starting your research career. Things that would have benefit you more in being a successful researcher. By successful, I mean having the most impactful contributions in your field.
I am not concerned about others being better than me but rather want to know how to become a better researcher and make better decisions that will contribute to that end. What are the things that you as a professional researcher would tell the younger you to do differently to be a better researcher.