I mean league is like all skills, whether if you're playing soccer or learning the piano, in a cooking class or doing academic research, it's about the attitude and the grind, that's all there is to it. The key to good mechanical play is knowing your opponents, i.e. their skills and their player level. Blitz skills: hook, knock up, silence, speed. Lissandra skills: dash, shard, root, stun/invulnerability. Aphelios skills: long range skill shot, root, minion wave poke, hard engage with crescendum, ultimate he'll use either to engage or to chase down. etc. And then there's player level at low elos players are just gonna throw a skillshot and hope for the best, at high elos they'll probably just walk up making you think they use it and then use it after you've exhausted everything.
If you are wanting some areas to look into keywords such as:
- dodging/landing
- kiting
- csing/vision
- predictions
Are some of the micros you'd be looking to learn. Once you get a bit more familiar with the game, like once you get to silver/gold you can start looking at learning about macros.
I guess the step beyond that is punishment. Playing against masters/ challengers even diamonds is pretty tough because they punish you hard for even slight mistakes. If you waste a flash they will gank you, if you use your only mobility ability for something else, they'll immediately all in you. If you disappear from lane to ward they will remember it, if your jungle pathing is too predictable they'll ambush you at your next gank. At high elos even a single minion xp missed 5 waves ago, or not remembering twisted fates last picked card can kill you. So yeah, that's something to look forward to.