Note: This procedure involves editing a game file; create a backup copy of the file before proceeding. To edit stats of your skirmish player, use a text editor to edit the "[player name]skirmishstats.ini" file in the "c:\documents and settings\[user name]\application data\my battle for middle-earth files" directory and edit it accordingly.
To make a Troll more powerful, have it pick up a tree as a club. It is slower, but much more powerful. To make an Ent more powerful, have it to pull boulders out of buildings or rock piles to throw at enemies. This is a very powerful long-range attack.
The Evil factions of the game both have a Spying power they can use. However, Good factions have no spying power. Early in Skirmish mode, recruit the Hobbit available to you. Have him run over to an enemy castle, camp, etc. He should be able to make it to the citadel, unless the enemy is playing a Good faction and has closed the castle gate. Once inside (or outside the gate if it has been closed), activate his Elven Cloak. He will remain there, untouchable by the enemy. By doing this, you will have a permanent spy. Note: If he moves, he will be exposed until he can use his cloak again. When selecting all your units by pressing Q, hold [Shift] and deselect your spy before ordering everybody to move or attack.
If you have reached your command point limit during a mission, send out a battalion or two (with the Banner Carrier upgrade) of soldiers. Have them fight until there is only one or two men remaining in the battalions/hordes. Then, send them back to your base, near a Healing Well for the Good side. You have just freed up several command points. Your damaged battalions can regenerate. Use this strategy to make up to three battalions of cavalry to raid your opponent with.
Train a horde of Archers and give them the Fire Arrows upgrade. Send them and shoot the Ent until he is on fire, then run away. He will die in a short time.
When you are fighting Isengard, either use Summon Rohan Allies or start out as Rohan. Build a stable and a lot of farms. Close the main gate and build a Postern Gate instead. Build an army of Riders Of Rohan and walk over the Uruk-Hai's. To counter battering rams, use Yeoman or Elven Archers. To counter Warg Riders and Siege Ladders, use Heroes or Sentry Towers. Note: With the riders, just ride over the Uruks. It will either kill or stun them for you to finish. With the riders, try summoning Eomer to the field and give them a bonus or two.
When Isengard, Pikeman can easily defeat Cavalry if their numbers are similar. However, by combining a Pikeman horde with a Crossbow horde you can have one of the most powerful anti-Cavalry groups there are. Additionally, with Mordor, there really is no cheap way to deal with Cavalry. Trolls and Mumaks are your best bet, considering they have heavy damage with little harm done to them. Try getting creative and putting Orc Archers with fire arrows inside the Mumakil. This can make for a devastating blow to even a castle, and not just enemy soldiers.
An effective siege strategy for Gondor is to build a good sized unit of Tower Guards (four or five battalions recommended) and as many Archers as possible. Put the Archers into one group and the Tower Guards into another. Make sure both groups are fully upgraded if possible, but choose Heavy Armor if you can only have one. Then, put the Tower Guards in front, with the Archers trailing close behind. Once you find an enemy encampment, have your Tower Guards move toward it and put them into Shield Wall formation once they get very close. Your Tower Guards can absorb an incredible amount of damage while in Shield Wall and will take the brunt of enemy attack, leaving your Archers free to wreak havoc.
Similar to Mordor, Isengard relies mostly upon a brute force with some variety. Always have at least six Siege Ladders and three Battering Rams. Make sure to have several combo battalions. Since you haven no castle walls like the forces of good, you will need a few Keeps and Guard Towers. Once you have all of this completed and about 100 to 150 Uruks, begin with the upgrades; they are essential to a swift victory.
Mordor relies heavily on massive armies and blind destruction. However, you are limited to only so many command points you have. You must create variety in your troops when needed. On most levels, you will have to siege some kind of castle. Always have a few Catapults and Battering Rams (a Siege Tower or two would not hurt). Always devote about 50 to 100 command points to siege weapons, as this makes most online players easy prey. For the rest of your command points, make a lot of Orc Warrior-Orc Archer hordes and several Trolls. Once you have this completed, spend your resources entirely on upgrading your troops and base.
When starting a campaign, build at least two or three Farms or Slaughter Houses. Also, make sure that all your men are guarding the castle (put them all around the base), so that no enemies or trolls attack you.
Hordes/Battalions with a Banner unit should be retreated when only a few remain to allow the ranked unit to regenerate.
Always close your Castle Gate and build a Postern Gate instead.
Try to grab as many of the economy/outpost plots surrounding your base.
Fewer upgraded units are always better than many non-upgraded units.
Build two economy structures per one unit production building.
Build economy structures in the back of the Camp/Castle and build unit production structures in the front.
Small cavalry is better than a large infantry, except against archers.
Do not blindly put any group of soldiers against any enemy soldiers. If you have cavalry, make sure to have archers as back-up against pikemen and the like.
In skirmishes, build a wide variety of hordes, but mainly use Archers and Monsters above Foot Soldiers. Always have all Heroes before an attack. Keep gates closed and heavily guarded. When all allies are defeated, use specials to summon units like Summon Ent Allies or Rohirum Allies. When raided, build as many Orc, Oruk, Gondor, and Rohan archers as possible. When you are outnumbered and other units that you control are far away, run away.