Have you contacted existing NGOs/charities to see if you could partner with them? That is exponentially easier than setting up your own entity and raising money for your efforts.

You could potentially create a program of your own underneath an existing organization, and take charge of raising your own funding (but allow them to run it all through their books so they handle all the reporting, tax filing, etc). They would likely need to take a percentage of all gifts secured to cover their admin costs but it would likely still be far less than you would spend setting up on your own.

In terms of donors ... the best place to begin is your natural network (friends, family, and companies where they work). You would then need to track and report all of your outcomes from your work so that you can eventually qualify for a grant funding, which might also be a good path.