In addition to what Josh said...
In the old days I would have been inclined to VTC "what are the common pitfalls" as "not a real question". Several alternatives suggest themselves: "how to avoid common pitfalls" would improve it, "how to avoid this specific common pitfall" is even better, but by then we're going away from what seems to be the intent of your suggestion.
Related to this, it's just far too broad to generate useful answers: "OpenGL" on it's own is a huge topic with huge variation between different GL_VERSIONs. Even the buffer object APIs can be completely different in GL1.5 code versus GL4.4 code. With compatibility contexts you can say "this pitfall can be avoided by just not using buffer objects", with core contexts you can't. Any concievable answer is going to be of use to only a subset of potentially interested people.
Despite all of this I gave your question a +1 because I believe that it is a topic for which useful questions with useful answers can and do exist. The problem is that a single, broad, all-encompassing question is just not the right thing here. Plenty of questions about OpenGL buffer objects already exist on the site, and can be found via the search facility, and people should be encouraged to use that to see if the pitfall they're encountering is one for which a solution may already exist.