Are you familiar with Givewell? They rate international charities for efficiency. Their model tends to prefer medical interventions over economic interventions (malarial bednets, deworming, etc) which I am not entirely sold on, but they are admirably transparent in their methodologies, so it's pretty easy to decide for yourself whether you agree with their evaluations.
If you want to investigate more broadly, "effective altruism" is the search term you're looking for.