Give money to NGOs who have an established presence in the hurricane-affected location. Do not fund exploratory teams or organizations that will start new offices to handle hurricane relief. Nearly every major relief agency is already established in Haiti, because of the earthquake.
Do not send stuff. No clothes, no canned food, no bottled water. Not even if a diaspora group or an embassy is calling for it. Give money to organizations who can respond right away.
Do not fly over to help. Not even if you’re an infectious disease doctor or a trauma surgeon. Especially not if you just want to offer a pair of hands. To actually help, you need to know the local context, which means you need to be local or you need to have a really good fixer. If neither of those things are true, take on an extra shift at work and then write a check to a relief agency with the extra money you earned.