Them most important thing to learn first when approaching elo in my opinion is learning how to build pill advantage and learn to avoid those 5050s. Once you learn pill advantage the next thing is analyzing the weekly elo meta. Why are players using x deck and why are players combining x deck with y deck.
And on the 5050 decision making...yes being random sometimes can get the win not going to lie. Or if you want to increase you win% higher to be a consistent top player is making a player log sheet. I do this when I'm only in the 1300 elo range as its easy to get there. So when I'm in a match i enter the players name in his log i made and write down all his moves and pilling so i have a logged data sheet of all of the players tendencies. If down to a 5050 i know if the player likes to pill out on his first option, he likes to play safe with a 1 pill, he likes to safely match my pills, and etc. I don't do tho for 1000-1299 elo as its to long of a process and simply playing pill advantage will get you to 1300 in no time.
No I'm not a "pro" player. Ive topped100 only 2 times but i consistently get to 1300 no problem. Time is an issue for me during the week but if i had more time from thurs-sun I'm sure my elo would be consistently in the 1370 range