Buy a proper instant read meat thermometer and learn about carryover heat. Seriously, just cooking meat to where it needs to be and no more makes such a difference when cooking.
Along with that, learning when things need to be cooked to higher temps for structural reasons.
Finally, learning how to get good browning or crust formation. Its all prep and heat control but damn a steak with a good crust is life changing.
Same. Its so nice for consistency. I also keep a basic knife sharpener in my cooking bag.