By now, you surely know that having leadership positions is advantageous in the college admissions process. That said, self created, senior year, uh-oh better get something to put in the “positions held, honors won or letters earned” column, short lived leadership positions are not always helpful.
If your school lacked a yearbook and you managed to secure funding, select faculty guidance and recruit staff in order to create one, that’s big. If your school is a new charter school and you were the first student government president, that can be big too. If, on the other hand, you created a card playing club because you felt your school lacked the necessary social outlets that card lovers needed, and by doing so, you have weekly meetings where you play card games and discuss your enjoyment of different games, this, as an example of leadership, is not necessarily going to help you get into college.
I do not mean to discourage you from starting card playing clubs, knitting clubs, movie clubs etc, but do so because you think it’d be fun. Start organizations that harness your passions and allow you to meet new people, teach others, and above all else relax (a word probably not often uttered during senior year). If you do so, call these efforts what they are. It will be much more believable if you start a social club and celebrate it as a social club, rather than try to spin it into an experience in leadership, governance, and management.