It's great that you are thinking about extracurriculars and how they may affect your chances at employment. All of the answers so far have been spot on and are great advice. The one additional point I would like to make is that any extracurricular activity you do should be something you are passionate about. It isn't worth doing something just to put it on your resume if you don't truly care about that activity. If you truly care about the things you do outside of school, you will be much more effective in explaining those activities to hiring managers/recruiters and they will sense your enthusiasm and authenticity!