Find a save point and save. All your players will have full health and Action Points. (HP & AP)

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.

Any treasure acquired in Evil Mode can be transferred to a regular saved game.

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.

Start a new game and find a savepoint and save. Next, do the Osgiliath level in Evil Mode and when you win you will recieve The Sword of Isildur. Save this on your newly started game and then you will be able to equip this sword with Berethor. Btw it does 205 damage.

When you are against the witch king at Pelenor Fields the easiest way to defeat it is by having Berethor, Hadhod (Make sure to have his 2nd Age Dwarven Mithril Piercing Axe and The Dwarven Mithril Helm) and Eadon. With these three, use these attacks: Berethor's Stunning Strike and Ecthelion Wrath. Hadhod's Mountain Rage and Eadon's Enraging Blow and Rohirim Rage. You will beat him in no time.