Somewhat unconventional (and i'm not really a seasoned reverse engineer so take it with some salt) but I started by hacking old video games (nes, gameboy, arcade.. that kind of thing). You could start with making basic action replay RAM cheats to e.g. give Mario infinite lives, then you can use breakpoints, the debugger, and a 6502 ISA reference to edit instructions and make ROM patches.

from then you can use things like Ghidra (which supports a lot of those old CPU arches) for more advanced analysis and make the game do almost whatever the hell you want if you have the patience.

I think a lot of the skills will transfer quite well (obviously not 1:1, you will need to learn some things) to the more employable side of RE if that's what you're interested in

Thanks! I have been "hacking" with games in the past (getting infinite lives and such) or bypassing some licence check (back then it was with OllyDbg).

I guess I'm struggling to transfer that to "real-life" scenarios. Like getting something useful out of reverse engineering (getting infinite lives is interesting to see that I can tamper with the game, but it's not exactly useful).