Age of Empires 2: The Conquerors Expansion

The Turks have a 8+5 bombard tower range. This is good for placing out of range of 
enemy castles and towers and destroying them without harm.

Always have villagers travel with your army. That way when an enemy tower or castle 
goes down you can build (if you have a lot of resources) the same building you 
destroyed. This is a good defense mechanism; then if they go to attack you, they 
will run into your towers.

The best unit is an Elite Teutonic Knight, you only need fifteen of them to take 
out an enemy castle.