Undergraduate discussion.

just concentrate on getting a high GPA and try to get a nice job lined up after graduation

A collection of most of the ideas given by others, to summarize-

1) Good Academics
2) Participation in extracurricular Activities - volunteering (like you do), starting volunteering group in University. Colleges are breeding ground for ideas and energy, try to leverage it by forming community groups and help the causes that matter to locals. Active involvement in everything that interests you even if you are leading all or most.
3) Working with professors to organize university events, research talks. Reaching out to people on LinkedIn or other places and arranging range speakers in Academics/extracurricular activities. Even calling a person who travels and makes a living out of travelling kind of speaker is also a proactive leadership example. Profs will remember you when you go for recommendation.
4) Getting into a job that you are passionate and continuing to volunteer in Employee engagement and CSR( Corporate Social Responsibility) activities etc, these get you good visibility at work and recommendation letter from MD/CEO would surely add value.
5) Preparing for your GMAT - There is loads of materials/information on this, however a good GMAT prep company that will focus on you as person and help you build your profile in important. However this can wait while you are at work on above 4!!!!

Just live it out every moment, lead and contribute in any way you can at every level