The Newbie wrote:
Front line morannons with shield,
back line orcs with spear,
trackers on wargs for shooting,
Morannon Captain,
Drummer,
Ringwraith,
Spider Queen.
+1.
The 1/3 Morannon shield, 1/3 Orc Spear, 1/3 Tracker (either warg or not) is the most standard and efficient competitive based combination of troops for any Mordor army. As points go higher you add in Shadow Lord (usually on Fell Beast if points are 700+), Drum and Spider Queen. For cavalry you either take Trackers on Wargs or ally in Serpent Riders because they're the best cavalry in the game.
Oh and Mordor following the above won the 2009 and 2010 UKGTs