In regards to the map, a good question to keep in mind is “Why is this here?”. For instance, the wall makes sense for archers, but what’s with the water and whatever those blue-green tiles are above the water in the southern section? Why are there pillars? Why are there forts in the middle of a castle? Etc. Plan out how you want the combat to look like. Check out this topic and look at BlueDruid’s link to some YT video that makes good suggestions.