What philosophers/philosophical works should I read before I'm allowed to move about freely within philosophy?
Depends how you define 'freely.' The list of essentials for "I just wanna read Nietzsche, Heidegger, Arendt, Wittgenstein, etc." (aka majors) is so much different than "I want to be able to read the latest philosophy publications."
Furthermore, it also depends on what kind of philosophy you're looking to read. For example I'm can move pretty freely within the continental tradition, but analytic? Forget about it.
you may have a point as far as comprehending the writing itself goes but I think the person you replied to refers to something like the dramatic difference in scope, i.e. the focus on and thus required prior knowledge of those minute technicalities that are worked on within the analytic school
If you do plan to 'start with the greeks', be sure to avoid c_ck translators. Many insert facile personal interpretations, aesthetic flourishes, Often they seek moralistic palatability and functional "readability" over loyalty to the source material.
well, I'll warn you off Barnes' Early Greek Philosophy (penguin) from what I've read about it he seems to be biased.
I enjoyed and thought highly of Waterfield's "The First Philosophers" but it was a while ago.