I don't know if you are in high school or college. Either way, there are bound to be issues of concern at your school that you can campaign on. Let's look at the possibilities.
For high schools, there are many topics that arise that could be worth campaigning about, small and large. Perhaps your school cafeteria does not offer healthy food or does not offer sufficient choices for vegetarians or people with food allergies. Another issue that can arise is tolerance for diversity and respect for others. Are there groups that are given a hard time in the school, for example, a racial group or gay students? This can be a serious problem in a school. Are drinking or drug use a problem? Security today in schools is a major issue, given all of the violence we have seen in high schools. Your school security might not be very good, and you might have some proposals to make it better. Some schools do not support their sports teams very well, and this is an issue that might be popular. You might propose that the school provide a bigger budget for sports, rather than forcing students and parents to do so much fundraising.
At the college level, in addition to all of the issues above, which could be campaigned on at this level, too, you might want to address other issues, such as global warming. Your school might have major investments in firms that contribute to global warming, in the energy industries. If you are at a southern school, your school might display a Confederate flag. There are bound to be students who oppose this, although this could prove to be an unpopular position. Date rape is a serious problem in college, as are binge drinking and fraternity hazings. These are the pathologies of the times in college, and they are well worth addressing. Your school might have teaching staff you feel are not responsive to student needs. You could take this on as a topic, too. You need to ask yourself what at your college is unsatisfactory, and there is a good chance you will have a good cause to campaign on.