Like you said, you first have to learn to reason about a circuit. You'll need some broadly applicable skills that give you insight, not more connect-the-dots re

Like you said, you first have to learn to reason about a circuit. You'll need some broadly applicable skills that give you insight, not more connect-the-dots recipes or brute-force math. There are many insightful graphical techniques that enthusiasts can use with at most basic arithmetic and special graph paper. Probably the best skill investment you can make is learning to sketch on impedance paper. It will demystify passive networks, and it's a gateway to so many other techniques like Bode plots. Eventually you won't even need the special paper most of the time. I recommend getting one printed and laminated to use with a dry-erase marker. It's best to learn the analysis along with how to simulate it and take the measurement. The discrepancies will reveal problems with the circuit, measurement errors, and limitations of the models. Your sketches will show how it works, you'll visually see what needs to be done even before you know how to do it, and you can play with design ideas right on the sketch. There are of course many other techniques for different situations. If you use discrete transistors, maybe learn to sketch a load line and check if a resistor is bad using a multimeter. If you do radio, learn to do impedance matching with a Smith chart.