If poverty were distributed uniformly, "think globally, act locally" would be a reasonable approach. You know more about the conditions near you, altruistically helping people can combine with your own interest in a healthier community around you, and you can see the effects of your actions. But rich people live near other rich people. Your local community is likely income segregated, as is your region and your country. The poorest people around you are somewhat well off on a global scale.  Which means that if you "act locally" then those lucky enough to live near rich people get disproportionate assistance.
So: "Think Globally, Act Globally".
 Assumed audience: USA. The 2011 federal poverty line income for one person is $11,170. Someone living on half that has an income of $5585, which is more money than 85% of the world's population lives on.