Jay Conrad Levinson, known best as the father of Guerrilla Marketing, has talked a lot about community involvement. In fact, in a presentation I heard him do many years ago, it was at the top of the list of thing GM's need to do. Why? Because people like buying products from companies they perceive as giving back to the community.
So, look for a non-profit that's in line with something you believe in. It doesn't have to be the biggest on the block. When it comes to giving back, it's about what's in your heart. You're looking for an opportunity to contribute through your skill set, your time and with or without a camera in your hands doesn't matter. This is about getting involved and helping.
One note of caution though. A number of times over the years people have told me how they want to start their own non-profit. It takes a lot of work to establish an official 501c3 with the government. Often the reason somebody wants to do this relates to a family member or friend who has experienced something tied to the cause they want to start supporting.
My suggestion is to look around your community for a charity that's already performing the function in support of the cause you want to develop. You can always find a way to earmark funds you raise in somebody's honor and still give that loved one special recognition. Plus, you'll be raising awareness directly instead of spending time getting the approval for a non-profit. If at some point you have the time and resources, you can always start your own charity later on.
I've written this many times before...you're looking for the community to be good to you. Well, you've got to make sure you're being good to your community. You want to start building your reputation as somebody who's known for getting involved and giving back.