I found that, ironically, the more advanced my troops get, the more meleeing they do. My platoon firing guard units take considerable casualties against even AI militia in a shootout, yet with the Black Watch I routed 6 French line infantry units, all meleeing at the same time, in a epic fort siege. You'd still take a good number of casualties, but I think in melee the AI's stat bonus advantages are not as potent as they are shooting, so it might be best just to charge in after a volley or 2 if you're facing militia type units, it might help in keeping the xp you already gained. Otherwise autocalc till you're 5 chevrons

As for naval battles, I guess I'm one of the few that does better at sea than on land. After I lost 1 3rd rate in a autocalc battle with 18 frigates and brigs (rated as a "decisive victory"), I never autocalc again for naval battle. The last ship I lost in a battle I played myself was 2 sloops, against that insane pirate stack in the caribbean, way back in 1701 or 1702. Now it is the 1750's and even with not being able to use 2 stacks of ships of the line due to CTD, all my admirals are turning alcoholic because there are no more enemy fleets left to fight