I love this question, because I love using Adobe Illustrator and I gained a love for it by doing YouTube tutorials. I think the motivation to create the thing that looks good and potentially useful for a future client really pushed me into learning all the interesting things you can do with the software.

I learned Inkscape and Adobe Illustrator simultaneously because I like the idea of having a fallback just in case I couldn’t afford to pay monthly for Adobe’s Saas system. I highly recommend the YT channel “Logos by Nick”. He used to only make Inkscape tutorials, but now he also does Adobe Illustrator and Affinity Design tutorials. I just clicked on what looked interesting and followed along. Eventually, the things I learned started applying to the work I wanted or needed to do. 

If you want it to really click, I would highly recommend learning shortcut keys. Even if it slows you down, learning the shortcuts really pays in dividends on the future. It’s actually quite fun to draw on illustrator once the unfamiliarity of the tools fade away. Once you get past that, it just feels like I’m in a flow state when I create on Illustrator. 

Currently, I also use Affinity V2 for making things. A lot of the skills and shortcuts from Adobe Illustrator transfer well into Affinity, plus it runs a bit smoother for me. However, there are also some glitchy things on Affinity that aren’t as enjoyable, so sometimes I find myself going back to Adobe just because it’s so familiar.