Hi vengefulpickle !
I usually use the in-game replay recorder and most of the time my own replays
This helped me a lot with Quince, who -you know- has an alternate gameplan against some characters.
Instead of playing a moderate ammount of blodges (as he usually does against Val and Geiger), he can play -a lot- of them to deplete his opponent's hand from throws, and then K gets 100% winrate. You can't play it every game thought, you need to get an appropriate hand to exploit it.
Watching replays with a view on opponent's hand helped me to know when I could do that (on which character, with which handsize, etc.). And that's -far- more often than I used to consider !
I also compare what I would have played and what my opponent actually played. There is an huge gap between what people think about Quince (tons of dodges, infinite vortex loop, terrifying Patriot Mirror) and what Quince actually is capable of (doesn't dodge that much because problems of handsize, has sometimes to lie because he needs to keep his face card to continue to manipulate his opponent, Patriot Mirror costs tons of cards...). And playing around this bias is really effective !
Looking at my opponent's hand helps me to narrow the bias I have on their character (althought I'm still scaried about Geiger lol), especially guessing their hand problem. In rock paper scissors, one could play "Rock" 15 times in a row, but in Yomi you can't "Attack" every turn with decent follow up (except rushdown characters, but they can't throw every turn in compensation).
I also watch some youtube replays, but that makes me learn much more about players than about Yomi (mysticjuicer loves to block, snoc focuses much more on building his gameplan than on disrupting opponent's one, etc.). IMO chatting with other people about strategy (after a match, on the forum...) is much more effective.
My personnal advice to progress on Yomi : don't play against yomibot, play sometimes on quickmatch and participate to as much tournaments as you can !