The top of the screen will indicate when an enemy will attack. If it is the same type of enemy, the attack order will always be the same. The center will attack first, followed by the left, then the right. Use this knowledge to target your attacks. Try to kill one enemy in the first round before it manages to attack. Consider by starting to attack the enemy troop that will attack last. Try to kill enemies one at a time instead of spreading your damage out to all of them. Enemy troops will tend to attack a specific troop repeatedly. Consider if it is just better to defend or to cast a healing spell on it during the second turn and have that troop healed constantly. It is better to your troops alive instead of spending resources resurrecting them.
Health
Besides consuming health potions from your inventory, you can return to the castle and heal your troops by spending silver. Save your health potions for emergency situations. Recovering at the castle will also refill your energy bar. However you will have to spend stamina again to return to battle.
Resources
After an area is completely conquered, its resources will be regularly awarded after a certain amount of time.
Troops
Other players can attack and try to steal resources your resources. Your garrison is automatically populated low level heroes. Supplement it with some high level troops. You can elect to spend 5 silver per troop to assign your best troops to your garrison prior to logging out. You can then reassign them back to your army the next time you play. To disband any of your troops, place them in your Hero’s army, then move it to the castle (under the "Available Units" tab in the "Army Recruitment" screen. You will now have the option to sell that troop and get a small amount of silver in return. To improve your troops (by removing negative attribute such as clumsy, lazy, etc.), built the Mercenaries Guild in your castle.