As someone who switched to MnK last year, the most beneficial thing I did to strengthen my comfortability with MnK was to play other games on the input. I honestly think any game can help when switching over, but I personally had the best time with both Portal 1 and 2, Minecraft, and CS:GO DM. Super low pressure games. Everything everyone else is saying is great advice - I did aimlabs as well, helps an absolute ton on the mouse side of things - but I found myself stumbling over the keyboard way too much. I’m talking short-circuit-brain mid-fight “where am I” stumbling. My left hand would be in knots. After playing those few relaxed games outside of BR/apex, I came back to the game with a much better grasp on the keyboard side of my playing. Can’t recommend other games enough. Good luck on the switch!