it sounds like you're talking about wanting to start a non-profit organization. there are a ton out there already, so this is the advice I would offer:
Operationally:
1) Check out guidestar.org for other similar organizations in the area. You'll be amazed. There are usually way more organizations that you'd expect, it's just that the one's that are not faith based don't get as much press.
2) Find an organization that addresses an issue that you're passionate about and check them out on guidestar. If their program costs are 85% of their revenues or so (meaning that their administrative costs like salaries are less than 15% of their revenues), it's a good sign.
3) Go volunteer. See the ins and outs of what makes them tick. See how they operate. also, you'll get exposed to other organizations in the area. It's a small, tight knit community, typically.
4) If you still believe there is no organization in your community, then you'll be all set to start one up. I would discourage just running out and setting one up. Here in OKC, we have so many homeless non-profits that we actually had to set up another one (The Homeless Alliance) because they were doubling up on services and leaving whole sections of the population out in the cold.
Big Picture:
1) You have to be professional, you can't think "we're just a couple of high school kids trying to help a little." If you're going to ask anyone to donate any of their money AT ALL, you have a responsibility to them to be honest about how it is going to be used and to make sure you're making prudent decisions. If not, you cannot expect them to ever donate again.
2) I'm a big fan of being an agent of LOCAL change because I believe that is where you can do the most good. I'm all for raising money for Darfur, but ultimately you're just turning the money over to a larger organization to get the goods to the people and it's hard to control that.
3) I think you'll be surprised at how many non-assholes are actually out there, but it's all about how you approach them. Unless you're planning on starting a revolution, you'll see more results with a softer approach. People almost never change because someone tells them they are an asshole and they need to be kinder. You have to guilt them into it.
4) If you are going to commit to starting, you need to commit to following through.
I can't stress enough to go look for another organization in your area that is already satisfying the need that you want to address.
