IMO start with a recent book that spells out useful pointers to give the classics a critical read: "Debunking Economics", by Steve Keen. Keen gave a talk at Google a few years back that was a pretty good summary of what's in the book's first version. If you're into stats and finance also check out the author's finance classes on youtube. Besides a bunch of videos that cover what's in his book, there are quite a few o…
As an aside, I would also recommend reading Thomas Piketty's Capital for 21st Century. IMHO it gives you a deeper historic perspective on economics than just couple decades back.