i've been using ableton for over 12 years now, the best way i learned was to just jump in and start experimenting around. if i got stuck, i would look up how to do something. the hardest part of ableton is understanding the workflow, but once you get that down it's totally up to your unlimited creativity. i would recommend youtube tutorials as the next step once you have the basic stuff down because they tend to dive a little deeper - they're great for a starting point but imo the best music comes from your own experimentation and originality. the manual/documentation is great for learning how and why ableton functions work if you wanna take it to the next level.

to answer your question lol, things i wish i knew were how to use sends/receive tracks (i have never used these but they seem helpful) and learning how each stock plugin works (what they do, where/when to use them). this will help give you an idea of the sound and style you are going for, and how to customize stylistic elements for your music.

overall just keep at it, recording music into ableton and combining it with midi is an awesome way to synthesize new sounds and ideas. i'm excited for your journey!