How can I help the people of eastern africa?

I have always wanted to go to africa for a long period of time to help out with poverty and support charities. recently Ethiopia, Kenya and Somalia have been hit hard by the endless drought and this has given me my wake up call. Which charity do you recommend I should support? I have looked into save the children, unicef and islamic relief so far. who do i need to contact to ask about volunteering abroad? any other info and advice is welcome :)