Right now, in the appropriate biomes, one can find thousands of mobs from various factions. This is unrealistic, because it is likely that soldiers would not randomly wander around their home, but be more organized.
War Parties would be large groups of soldiers, often found near roads, patrolling the area. No longer would Gondorians randomly spawn and mil around. these would be organized, with a Banner Bearer and possibly a captain.
Some factions and biomes deserve a nerf in spawning.
The High Elves should be rare - there were only a few left by the War of the Ring.
Rangers of the North should be 1/5th as common, and Rangers of ithilien 1/2.
The Lone-Lands and Eriador (which means "lonely land") should have almost no spawning in them. However, orc and ranger War Parties could be rarely found.
Thank you for reading! I may think of more, so stay tuned. Also, feel free to remind me of any I missed, and give comments, Kudos, and constructive critiscism you want to offer.