Just finished module 4 (Tactics). For me, the most useful section was the one on “Why don’t I see these in my games, when I can do puzzles fine.” The idea that we simply don’t ask ourselves if a tactic is present is obvious in retrospect, but hit me like a jolt – that’s exactly what I don’t do. I’d like to add a couple of things: 1) always blunder-check your opponent’s move. It’s mostly the same thing as asking yourself if there is a tactic, but it’s a reminder that he can blunder, too. Second, if you’re studying an opening or have a preferred opening, the moment the opponent varies from what you expect, ask yourself if there’s a tactic. It may not be there, it may just be a weak positional move, but there’s often a good reason why that move isn’t played.