Wonderful that you are thinking about your future and fantastic that you want to help others. I'd suggest begin volunteering at various places to get exposure to many different options. For example, you could serve meals to the homeless, offer to read at a school for minorities, assist immigrants at an adult basic education program or help at a nonprofit event. There are endless possibilities if you search for them.
You may then decide on a career in the nonprofit world, social work or even a business setting allows you to help others. The more variety of volunteer experiences you have, the better your resume will appear and perhaps open up some new areas you may not have considered.
With every good wish!