Restore HP and AP
If you are low on HP or AP, find a save point. Save your game and both your HP and AP will be completely refilled.
Once your Elf healer gains the Valor move that presets whoever you choose with an instant revival when ever you die, use it at the beginning of each battle on her first, then on everyone else. If you maintain this so that no enemies can truly kill you, you will almost always be the victor.
Defeating the Balrog
Stock up on Elf Medicine before fighting the Balrog. Have Gandalf use it to bring you back to life; you will get more unit points back if Gandalf uses it on you. Also, equip any Fire protection Elf Stones you have. The Balrog has about 70,000 HP.
Defeating the Witch King
To defeat the Witch King at the Pelennor Fields, make sure that you have Hadhod's Second Age Dwarven Mithril Piercing Axe and the Dwarven Mithril Helm. When you face the Witch King, use these attacks: Berethor's Stunning Strike and Ectehlion Wrath, Hadhod's Mountain Rage, and Eaoden's Enraging Blow and Rohirrim Rage. The Witch King has 200,562 HP and 59,098 AP.
Transferring Evil Mode treasure
Any treasure acquired in Evil Mode can be transferred to a regular saved game.
Good sword for Berethor
To start the the game with a very good sword for Berethor (the first character you start with), do the evil mode of Osgiliath and save it on an early game. By doing this, you will get the Sword Of Isildur, which has a 200+ damage rating. At the beginning of the game, you can give at least 2,000 damage points from a normal hit with this weapon.
Get some of the best skills very early in the game, just practice. In the first level, find an enemy respawn point near a save point. Once there, keep attacking until you run out of AP and save the game. Your AP should have refilled, as well as your health. Keep doing this, and after a few hours you will get the special move from Berethor that can hit an enemy five times in a row. Note: This works for all characters, and not just Berethor.