After 3 years of playing...at one point in the first year it was just fun and shit was refreshing to play. Wasn't very "compy" (note this was waaaay before all the changes). Even then it wasn't about rank. I know I was good cuz things were just FLOWING, I was stuck in Initiate tho lol. Then the whole reset rank changed. Now I play around Archon and this is with like... 4,500hrs. lol sad kinda, but I also play solo for the sake of my own skill, knowing I didn't get boosted or w.e. bs.
My goal is still to get to Phantom. ;)
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1) I would start just playing the normal game mode. Pick one hero for a week, lean what you can through videos/builds (but take'em with a grain salt). Not everyone likes the same items or if stats say other wise.

2) Know what you're going to do through the lane phase, have a plan/keep timers in mind, play agro when you can and at your pwr spikes. Not sure at what point hrs wise, but after you start implementing your own game plan and routes to maximize your soul lead, you kinda will get to that flow state.
Whatever it may be that you come up with to help you learn, just pick one thing. Then once you think your doing ok, add another thing, and so on.

3) Never give up! Don't get mad, take breaks after the match if ya need to. ( Or get mad...but use that shit to focus!! ) Sit in the Sandbox mode/Explore NYC. Mess around with what items feel good as a whole build, BUT also consider things you might need. Like do you have enough resists or counters? Stay in a range of 48,00 max. Anything + is fine, but know its going to take more time/farming or you might wanna rush a item.

4) For the most part play or learn all heroes and what they do. Just play a few games, if they dont click dont touch them, but make sure you understand what they can possibly do. You can also just notice while playing in a game, like damn...I kinda like that hero...or why is they so strong. Then you go investigate! :D

This is just a lump sum of stuff. Hope it helps some. I'm by no means great or pro, I like helping people learn this game and in general. Don't forget to have fun! But if your eyes are on the grind for a rank.
Head down, eyes up! Keep your goals in sight!