Start with the bigger picture and decide what is a big problem you see and want to be a part of the solution. Once you know that, you can look at the different things you can do to help eradicate that problem.
For me it was helping the homeless. There are many ways to help homeless people, but I think the best way is showing them that someone still cares just if even to only help serve a meal. The St. Vincent de Paul Society has many things here you can do. I suggest serving meals where you get a chance to interact with them. The meal is great way to help at a basic level but where you can do these people the most good is to just smile and ask how their day is going... Show them kindness. Give them hope.
That is the way I feel I can best help the homeless at this moment.