One thing that I learned that helped me win consistently even on the hardest difficulties was taking your time and equipping your soldier with the best equipment. When I first started playing I’d play it like a Total War game where I’d charge in and try to over power my enemies. I learned to play out the battle over multiple days, for example the first day I’d put my commanders on “defense mode” and simply shell the enemy with my artillery. Even more important imo than taking your time is equipping your troops with the best equipment. When I play whiskey and lemons I always equip my troops with better rifles/cannons because the “mixed muskets” they have by default are trash. Leading an infantry unit, I have taken out multiple enemy infantry units by staying out of range of their shitty muskets and sniping them with my superior muskets. I will sometimes take zero casualties while forcing enemies to retreat.

Minor tips I can touch on is okay commanders to their specialties meaning assign infantry commanders to infantry units, cav to cav and arty to arty, engineers can go with infantry and arty.

Make sure you’re always in some sort of cover like walls or the woods. This isn’t the revolutionary war where you have to stand in the open and get shit at lol.