We're wiring up electronics for the Iron Man suit and before we got too deep into it, we made sure the actual soldering technique was solid.
The thing that gets most beginners is that the solder doesn't go on the iron. You heat the wire or surface first, then touch the solder to the other side of the wire, and it melts toward the heat. Pull the solder away first, then the iron right after. Do it the other way and the solder sticks to the tip and you've got a mess to deal with.
This is one of those things that sounds obvious once someone explains it, but the instinct is completely backwards when you're first learning.
Getting the principle right is the difference between a clean joint and a cold one that'll cause problems later.
Was there a specific moment when soldering started clicking for you, or for your kid if you've taught them?