There is no guide for this game yet. But apparently it is EASY POINTS! 

Check the article on EASY RANK wins.

War of the Last Alliance - 5 points

Complete the training level.

Battle of Helm’s Deep - 25 points

Complete the Helm’s Deep level in the single player "War of the Ring" Campaign.

Conquer over Isengard - 25 points

Complete the Isengard level in the single player "War of the Ring" Campaign.

The Mines of Moria - 25 points

Complete the Mines of Moria level in the single player "War of the Ring" Campaign.

Siege of Minas Tirith - 25 points

Complete the Minas Tirith level in the single player "War of the Ring" Campaign.

Battle of Pelennor Fields - 25 points

Complete the Pelennor Fields levelin the single player "War of the Ring" Campaign.

Assault on Osgiliath - 25 points

Complete the Osgiliath level in the single player "War of the Ring" Campaign.

Assault on Minas Morgul - 25 points

Complete the Minas Morgul level in the single player "War of the Ring" Campaign.

All's Well as Ends Better - 35 points

Complete the Black Gate level in the single player "War of the Ring" Campaign.

Assault on Mount Doom - 25 points

Complete the Mount Doom level inthe single player "Rise of Sauron" Campaign.

Siege of Osgiliath - 25 points

Complete the Osgiliath level in the single player "Rise of Sauron" Campaign.

Fall of Minas Tirith - 25 points

Complete the Minas Tirith level in the single player "Rise of Sauron" Campaign.

Battle of Weathertop - 25 points

Complete the Weathertop level in the single player "Rise of Sauron" Campaign.

Siege of Moria - 25 points

Complete the Mines of Moria level in the single player "Rise of Sauron" Campaign.

Razing of Rivendell - 25 points

Complete the Rivendell level in the single player "Rise of Sauron" Campaign.

The Land of Shadow - 35 points

Complete the Shire level in the single player "Rise of Sauron" Campaign.

Splintered Shields - 15 points

Kill 100 enemies in one life as the warrior.

Blade That Was Broken - 15 points

Score 30 hits on the combo counter as the warrior.

Blademaster - 20 points

Kill 25 players as the warrior in any ranked match.

Eagle Eyes - 15 points

Get 25 headshot kills in one life as the archer.

Rain of Fire - 15 points

Kill 25 enemies in one life with the archer's fire arrows.

Marksman - 20 points

Headshot kill 10 players as the archer in any ranked match.

A Knife in the Dark - 15 points

Use the scout to backstab 10 enemies in one life.

Fire and Slaughter - 15 points

Kill 25 enemies in one life with the scout's bombs.

Assassin - 20 points

Backstab 10 players as the scout in any ranked match.

House of Healing - 15 points

Heal 30 allies in one life as the mage.

Flame of Anor - 15 points

Kill 100 enemies in one life with the mage's fire wall.

A Storm is Coming - 20 points

Kill 15 players with the Mage's lightning in any ranked match.

Storm and the Lightning - 50 points

Score the most points on the winning team in any ranked online match.

A Red Sun Rises - 50 points

Kill 30 enemies in a ranked Team Deathmatch match.

Rings of Power - 50 points

Capture 3 rings in a ranked Capture the Ring match.

Ride to Ruin - 50 points

Capture 10 control points in ranked Conquest match.

Return of the King - 15 points

Defeat 3 Nazgul as Aragorn in Minas Morgul ("War of the Ring" Campaign).

You Have My Axe - 15 points

Kill 20 enemies with Gimli in any Team Deathmatch game.

You Have My Bow - 15 points

Kill 20 enemies with Legolas in any Team Deathmatch game.

I Will Take It - 15 points

Capture a ring with Frodo in a ranked Capture the Ring match.

You Shall Not Pass! - 15 points

Defeat the Balrog as Gandalf in the Mines of Moria ("War of the Ring" Campaign).

No Living Man Am I - 15 points

Defeat the Witch King as Eowyn in Pelennor Fields ("War of the Ring" Campaign).

Lord of Mordor - 15 points

Defeat Gandalf as Sauron in the Shire ("Rise of Sauron" Campaign).

Lord of the Nine Riders - 15 points

Kill 10 players in one life as the Witch King in any ranked match.

Never Toss a Dwarf - 15 points

Defeat Gimli as the Balrog in the Mines of Moria ("Rise of Sauron" Campaign).

The Way of Pain - 15 points

Defeat Aragorn as Saruman in Weathertop ("Rise of Sauron" Campaign).

Stupid Hobbitses - 10 points

Kill 300 hobbits in the Shire in one playthrough ("Rise of Sauron" Campaign).

Mithril Armor - 10 points

Complete any campaign level without dying.

Fellowship of the Ring - 10 points

Complete a campaign level cooperatively.

Secret Achievements

Unfriendly Skies - 10 points

Get picked up by a fell beast or eagle.

That Still Only Counts as One - 10 points

Climb and kill an Oliphaunt.