A couple of personal observations about NGOs based on my experience. Bear in mind, these are general, not absolute.
-Immediate disaster relief is significantly different than medium- and long-term development or reconstruction. The former is pretty straight forward, the latter far less so.
-In medium- and long-term development or reconstruction, smaller is usually better; it's probably not an accident that smaller NGOs did a lot more in Haiti. National, rather than international, NGOs are more likely to be staffed by natives who actually know how to navigate their country's bureaucracy, speak its languages, relate to its people, culture and needs, etc. Because of this, they have more of a stake in the success of the programs and are more likely to be effective. This may make it harder for well-meaning foreigners to identify such NGOs and requires a bit more knowledge and research.