if you have the time, try looking at an actual music theory textbook (Walter Piston's is pretty good, Aldwell and Schachter's all right). It'll be dry, but it'll give you a good general understanding of tonal harmony, of which contemporary "pop" tonality is a small subset. You'll get more used to not just specific chord patterns, but also the general ideas of "functional" harmony (where chords lead, or "progress," toward other chords in a hierarchy). A lot of other songs will make sense in a different way when you become more familiar with these concepts. i'd also say to get a good fake book and just play all the old standards that you can, while keeping tabs on the harmonic changes within.
hope this helps!
Mike