Ok, try to get old electronics from the pre 90's era with discrete parts (with markings) and schematics available online. A few old CRT TVs / PC monitors or test/audio gear that's defunct can also fill your junk box with a lot of useful parts. For CRT equipment, discharge all the caps etc. near the yoke with an insulated handle screwdriver or similar.
For the semiconductor parts you'll need to to a bit of basic testing to ensure they're serviceable. Bipolar transistors, FETs rectifiers, maybe even some opamps from audio gear. Having a curve tracer is a nice gizmo for precisely profiling simpler semiconductors but that might be a stretch right now.
Search on Bangood.com for cheap combo component tester kits to handle FETs, bipolars, diodes, caps, resistors etc for < $20. They work passably well and quickly, I use a couple of them for identifying parts from 'grab bag' collections etc.
When I started out as a teenager I did a lot of scavenging like that. Get a good desoldering tool (Hakko?) though, those manual solder suckers are finicky and splatter solder. For ICs and such you'll need hot air desoldering or solder wick. Keep any hot air under 280°C to not damage parts.