1) Also build units by combining new units with experience
units. New unit takes on the experience of the original 
provide the added unit has less members. This can be done 
by splitting then recombining. 

2) Always attack with a large army on one side of the enemy
and a small unit (cavalry is best) on the other. Make sure
the enemy has no adjoining units. Each victory then results 
in the total loss of the enemy unit.