Darius is a Champ who can do really lots of Damage. But he can tank too.
For the beginners i think that you do one round Coop.
After that you can do some rounds in Dominion.
Then you have trained this champ a little bit and can play normal Games for more Points.
When you be sure that you can play this Champ really good begin Ranked Games.

FIRST I MUST SAY: I BE GERMAN I CANT SPEAK ENGLISH VERY WELL!!!

Greater Mark of Strength : This Runes give you "+0.95 Attack Damage"

Greater Seal of Resilience: This Runes are for "+1.41 Armor"

Greater Glyph of Shielding: This Runes give you "+0.15 Magic Resist per lvl (+9.72 at lvl 18)

Greater Quintessence of Intellect: This Runes are for "37.5 Mana"

Ok, you begin with the "Boots of Speed" and 3 "Health Potions".
When you have 1815 Gold or you die buy "Ninja Tabi" and and "Phage".
Then you buy an "Giants´s Belt" and then you can make the "Phage" and the "Giant´s Belt" to an "Frozen Mallet".
After this time, you must be lvl 7 or higher.
Now you can buy an " Maw of Malmortius" and again an "Giant´s Belt".
For the End you buy some regenerative life. The "Warmog´s Armor" give you really lots of Life and Life regen. Your penultimate Item is and "Force of Nature" to have really lots of Life regenaration. The last Item is again a "Warmog´s Armor"

You begin with "Decimate" ( Spin to win ) :D "Q"
Second Skill is "Apprehend". "E"
Third Skill is "Crippling Strike" "W"
Fourth Skill is "Decimate" "Q"
Fifth Skill is "Decimate" "Q"
Sixth Skill is "Noxian Guillotine" "R" Your Ultimate
Seventh Skill is "Decimate" "Q"
Eighth Skill is "Apprehend" "E"
Ninth Skill is "Decimate" "Q" This skill is finished!
Tenth Skill is "Apprehend" "E"
Eleventh Skill is "Noxian Guillotine" "R" Your Ultimate
Twelfth Skill is "Apprehend" "E"
Thirteenth Skill is "Crippling Strike" "W"
Fourteenth Skill is "Apprehend" "E" This Skill is finished!
Fifteenth Skill is "Crippling Strike" "W"
Sixteenth Skill is "Noxian Guillotine" "R" This Skill finished your Ultimate!
Seventeenth Skill is "Crippling Strike" "W"
The last Skill is "Crippling Strike" "W" This skill be finished!

Hemorrhage - Darius aims his attacks strategically, causing his target bleed. This effect stacks up to five times.

Decimate - Darius swings his axe in a wide circle. Enemies struck by the blade take more damage than those struck by the handle.
Deals 70/105/140/175/210 (+0.7) physical damage to all nearby enemies in a circle. Champions in the outer half of the ability are struck by the blade, taking 50% additional damage.
Cost: 40 mana
Range: 1

Crippling Strike - Darius's next attack strikes a crucial artery. As they bleed out, their movement and attack speed is slowed. Crippling Strike's cooldown is lower the more bloodied its target.
The next basic attack deals 120/140/160/180/200% damage and slows the target's movement and attack speed by 20/25/30/35/40% for 2 seconds.
Crippling Strike's base cooldown is reduced by 1 second for each stack of Hemorrhage on the target.
Cost: 30/35/40/45/50 mana
Range: 0

Apprehend - Darius hones his axe, granting him passive armor penetration. When activated, Darius sweeps up his enemies with his axe's hook and pulls them to him.
Passive: Grants 5/10/15/20/25% armor penetration.
Active: Pulls in all enemies in front of Darius.
Cost: 45 mana
Range: 540

Noxian Guillotine - Darius leaps to an enemy champion and strikes a lethal blow, dealing true damage. This damage is increased for each stack of Hemorrhage on the target. If Noxian Guillotine is a killing blow, its cooldown is refreshed.
Leaps to target enemy champion and strikes a lethal blow, dealing 160/250/340 (+0.75) true damage.
For each stack of Hemorrhage on the target, Noxian Guillotine deals an additional 20% damage.
Maximum Damage: 0.0.
The cooldown is refreshed if Noxian Guillotine kills the target.
Cost: 100 mana
Range: 460

I think the best Spells are "Ignite" and "Flash".

"Ignite" : This Spell you can use when a enemychampion want escape! You press "D" or "F" for "Ignite" and click on an enemychampion. He gets a little bit of Damage and with luck you get the kill.

"Flash" : This Spell you can use for escape! When you press this Spell you jump to the Place where your mouse is. With "Flash" you can jump about Walls/Turrets/Minions/Champions.....

When you think that you can play Darius really good you can start with Ranked Play!
BUT BE CAREFUL: In Ranked Games really much player said: Ban Darius pls!
So you must say early that you want pick Darius and go on top or bot lane.
When you be in Ranked Game you must go to the Top lane. That is the best lane for this Champion.
You must play def because much people go jungling in Ranked Play!
All said pls go Solo you be OP Champ.
So play Defensive and dont run behind Champs for the Kill. When you be ganked or when you die your Turret be lost.
When you have a Chance to destroy enemyturret: Dont attack enemyturret when you play solo-top. you push the the lane that your minions can attack the turret. You go Mid-lane when the minions attack the turret. You help in mid lane to gank the enemychampion and after that you can go back to your lane. When you dont want gank then port back to base for buying something or heal mana/life. When your minions are dead you must go back fast to your top lane. And when the enemyturret be destroyed you can help mid or bot lane to push. When you help push you can attack the turret. But be careful: In Ranked Play all gank at the turrets!
When you all have good teamplay you can destroy all enemyturrets and win this game :D
NOTICE: DONT FOLLOW ENEMYCHAMPIONS WHEN THEY HAVE LOW LIFE!!!!!!!!
Have fun ;)

Pros: Darius do lots of Damage with his Skills! With his Ultimate he can do a pentakill easy.
He be one from the best Teamplaychamps and can steal really good so you can do lots of Kills.

Cons: He cant run so fast and be ganked really often. You must play defensive that you dont die. His normal attacks dont do much Damage.

I recommend: DONT GO JUNGLE :/ Much form the Summoners go jungling with Darius. That is really bad :X He cant jungel good and he be a Lane Champion. But you can gank often with Darius :D

Darius be a really good Teamplayer and can help often with Ganks!
Normally you go top lane with Darius and help gank mid lane :D In Teanfights you can have all kills when you do your ultimate for steal last hit ;) All say steal but you never see them again : and they cant report you for that :D But dont say sry or teamwork or other. Then they can report you.

Your Ultimate is fantastic. You ave never Cooldown when you only do last hit with this Skill.
You can do "Apprehend" and then "Crippling Strike". Then he be slowed and when he be in range for your AXE you press "Decimate" and do lots of Damage. When he has low luife oyu do Ultimate and get the kill.

You must search for minionfarms all the time.
Yeah kills be the best thing for make money but you must ever do minions because your "Decimate" do lots of Damage and you can kill the farm really fast and get hundreds of Goldcoins.

Darius be an really good Champion but you must learn him. He be the best killer and can kill farms really fast but when you cant pay him or have fail build ( Bloodthirster or B.F Sword )(Damage and Ability Power) you can give up this Champion.


For the end i must say : SRY FOR MY BAD ENGLISH! I cant speal english very well i come from germany. But i hope you enjoy this Guide and i am looking forward for good votes :D