This is a good idea to set the battle up how you like it. Cast spells like Blind and Haste at the beginning of each round so that they last longer. Don't attack blinded creatures, as it'll release them from their paralysis. It is a much better alternative to attacking them in melee combat. This'll make the archer run and attack another enemy with his melee weapon.
Most archers deal half damage when attacking with their melee weapons.
Some dragons target two squares, hydras attack all neighboring squares and Harpy Hags return to their original hex after attacking, therefore eliminating all counterstrikes. By learning these traits, you can increase your success in battle, as well as your chances of surviving the battle with more and more troops. This includes getting all the Town Hall enhancements, Fort enhancements, Blacksmith, Resource Silo and Level 1 Mage Guild at the start for all towns that you control. The trick is to maximize your creature output - you can always upgrade them later. Individual troop production increasers should be built when possible, since they greatly increase the number of creatures outputted.