When fighting in the middle of woods, place your troops so that they are all hidden by the trees and not on the enemy's way. Then place your general next to a border or very far from enemy and wait for them to come after your general. Keep your troops ready and tell your archers to use flaming arrows and fire only at orders.
When your troops face the enemy army's backs make all your cavalry charge the enemy general, tell your archers to fire at will and concentrate fire on every "wavering" unit.
Order your all your infantry to attack at the nearest troop(not the enemy general, let your cavalry handle then), and watch out for the enemy's morale. When you see any unit wavering, make all your archers fire at them even if your infantry is already on the middle of the battle. Usually one volley will be enough to make those cowards remember they have a business meeting somewhere else.
When the enemy stop moving a begins fighting your men, it good to have your general near them so that, if you have high chivalry, they stand their ground or if the opposite, inspire fear on the enemy's hearts.
By the time your cavalry murder their leader, their units will begin to rout, then forget those bodyguards and make your cavalry hit every single unit who is wavering.

Make sure you are not near your computer, because this is surely going to spit blood everywhere on room.

Works even better when outnumbered! Just prepare to get several experience points (My record was seven with Newbie Prince Rufus).