Choose based on principles you will still respect if the outcome disappoints.

Outcomes depend on luck as well as judgment, so judging your choices only by results will teach you the wrong lessons. Deciding by principles you would still stand behind after a bad outcome gives you something stable to hold when things go wrong. It also spares you the corrosive regret of a decision you never believed in.

Before choosing, ask whether you could explain your reasoning honestly to someone you respect if it failed. If the answer is no, the reasoning needs work. If yes, you can accept a bad result without it becoming a bad conscience.