It is often said that adults learn best by doing. But at times, there is an even more powerful learning method: judging the quality of work of others.
Learning by doing is an important tool. An even better way to learn is by judging. If possible, put yourself in a position to critique the work of others. You need to have some idea of how to do the thing you are judging, but you do not need to be an expert (particularly if you will be doing the judging as a member of a team, with set criteria in place.) Just jump in and think of it as an active learning experience. The expertise will come with the experience.
Taking things to the next level, you can become an instructor or teacher. Obviously, you should be comfortable with the topic you are presenting, but no need to be an expert. It is said that to teach, you should know three times the amount of information you give out…. and, in the process of preparing for and giving your class, you really learn what you will be teaching.