Understanding basic electromagnetism and AC and DC as
>>11602393 anon said. As several anons have said, experimenting with a breadboard really really helps.
What I like to do is write a simple block diagram first, leaving out component values and just understand what I'm actually looking at. Then I fill in component values and start looking in more detail at circuits within the circuit (i think of them as subcircuits but this probably is not a real term).
If you don't understand coils/electromagnetism, look up various electromagnetism simulators. There are free demos on 1990's-looking websites that suffice. If you don't understand capacitors or diodes, you should genuinely go through some very, very basic info. Any college-level physics textbook can explain these things. A lot of people like to use analogies to more obvious physical phenomena (like water pressure to explain voltage) but I think these analogies suck because voltage isn't pressure it's potential difference, there's a really wide berth between those two concepts and if you get it stuck in your head that voltage = electrical pressure things will get less and less understandable as you go on.
Focus first on electrical fields and field diagrams. Start with point charges and then move to simple circuits. You should know how to do practical calculations like power dissipation of a resistor, where Ohm's law is applicable vs where it is not, etc. Start with electrical fields and THEN go to electromagnetism, your brain will thank you later. Foundations are important. Diodes are a lot simpler than opamps. It's a language like anything else; familiarity lends to understanding. I started out working on my own guitar amps, I barely knew what I was doing except for safety since I've worked on computers since I was a kid. Years later, looking at schematics of amps that I already built (by following instructions with my monkey brain) I was able to understand more of what was going on. Always learning, tho.
