Any advice on how I can get to do what my pion is.?

I am 18 years old studying journalism on my first year and I thought I would absolutely not regret it as it is one of my pions; writing. But I don't think it was for me, not now. I feel like I really want to be part and involve myself in humanitarian work..I love the idea and I love making others happy and helping out and I KNOW there are people out there that need help. I just don't know how to get started with this. This is a strong pion of mine, I'm a fair person and don't believe in unfairness. My role model is Martin Luther king, Gandhi and John Kennedy. I am christian ( catholic) with a big Buddhist influence in me. I am a vegetarian also.I really don't know how to get started, please give me some advice. Thanks for your time.