The easiest way to beat goblins is to rush them with your infantry while your archers snipe. (and if you have wardogs and are worried about the number of goblins you are facing, set the dogs loose!) If you waste time using shield walls and setting spears waiting for them to advance, your group will be decimated. You must play them the exact opposite of how you play bandits or direwolves. They are skirmishers so they want to keep separation from you. Deny them the space they need and thery are easy kills.