The wolf can be considered an opposite of the pikeman, having low defense and high attack abilities. Their double attack ability assumes there is a retaliation in-between, so try to get the targeted enemy to waste the retaliation on another stack, ensuring that the wolf will not get hurt in his weak defense. The wolf's speed is very good, so the creature can be kept far away from the battle and ordered to charge suddenly, ensuring it will attack first.
When fighting a Barbarian army, try to get rid of the wolves quickly because, while presenting a big threat when attacking, they cannot take much damage. The wolf is the only fast Plains unit, so they are very well suited to go with Barbarian scouts, who are very good pathfinders on rough terrain.