You should always assess the outcome of a fight in every scenario. From the formation of troops to the enemy's formation and what they are going to focus on taking down first. This should be a thing that will come naturally once you learned how every class works, so don't stress over it from the very beginning, but keep an eye out and remember everything that you see. Monsters don't tend to go out of their way to take down your most powerful characters, because that's how the game AI works, so they tend to follow the same path every fight. If you know what to expect from them, try to either use that to your advantage, or minimize the damage by sending in more infantry troops.