NGB's GI Bill guidance.
First register for GKO access. CAC not required, but makes it much easier to deal with.
The site is particularly relevant for those trying to crack the code on the Chapter 33 (post-9/11) GI Bill. This resource is probably better than even the VA's own website on this topic.
This Chapter 33 GI Bill is an instance in which Google is not your friend. Only use official sources. This is too important and too delicate to use any other sources.