Looking for tips to improve.

I've been playing hearthstone for months now, and have a fair collection, I made it to rank 13 once, but ever since then even constantly tweaking decks I seem unable to get past 18.

The biggest thing for me is the Knights of the Frozen Throne release, rank 20-18 is just absolute madness, it's filled with Evolve Shaman, Freeze mage, elemental mages, exodia mages/paladins, Demonlocks, basically everything. It feels impossible to move forward, there doesn't seem to be anything that is solid enough to deal with literally everything.

With all that said i'm not looking for a magical fix to legend or anything, I just feel like i've hit a point where no matter how hard I try I can't seem to improve. I know I make mistakes, I take the time to notice them, mark cards that don't work as well and replace them, keep track of what destroys me, what doesn't ect.

This isn't a rant or anything, i'm looking for honest feedback, places to look for guidance, improvement ect.

I try to watch streams and YT vids such as Kripp, but really haven't been able to retain much from them. I realize the game takes ALOT of strategy, and maybe i'm a bit incapable of following the Meta and adapting to it no matter how hard to try, I guess I just need a starting point.

Thanks to anyone who's taken the time to read this, any feedback would be appreciated.