Let me be more specific. How familiar are you with terminology like essence, energy, nature, hypostasis, will, species, genus, property, accident, enhypostaton, etc.? In other words, how fluent are you in the terminology used by the Greek fathers?
If these terms make your head spin, I would definitely recommend that you pick up St. John of Damascus’ The Fount of Knowledge (You can get it on
Amazon for about $15 plus shipping and unfortunately tax if you also live in Texas, though I’m sure other places might also carry the book, but really $15 for a translation of a patristic work is dirt cheap). The translation itself does quite a good job in preserving most of the Greek terms, however, I dislike how it translates the term energy sometimes as operation, other times as actuality, and other times still as act. It obscures the relationship between these concepts in Greek, but overall, I think that is a rather minor flaw. The actual work itself is nice because it is patristic, it is basically a summary of all Eastern thought up to that point in time, and if I recall, it was written as a sort of crash course in theology.
The first book, The Philosophical Chapters, is basically a crash course on the terminology used in Greek philosophy and also by the Greek fathers. It is somewhat dense, but incredibly helpful. The second book details all of the Heresies which the Church had known at that time. The third book (itself split into four books) is an Exposition on the Orthodox Faith which explains a whole range of things, on the Trinity, man, Christology, and even a short segment on why the veneration of icons and relics is permissible.
If you are somewhat familiar with Patristic Greek terminology, then I might recommend John Meyendorff’s Byzantine Theology (also on Amazon for around $20-30).
If you are rather advanced in theology and philosophy, I would still recommend the Meyendorff as an overview, but if you have other interests that are more specific, let me know and I could probably think of some other books that are a bit more specific in their scope.