While fighting under the Angmar faction, build a few Mills. Then, build a Hall Of The Kings Men. Train a two to four Dark Rangers. Build the Armory and upgrade it to level 2, then research the Ice Arrows for an extra boost in damage. The rangers will kill your enemies very quickly. Beware of Cavalry units. Train some Thrall Masters with the Spearmen and use them to defend the rangers until you can build up a large enough army and defeat your enemy.