Irelia is one of the best initiator in the game, who could make or break any team fights depending on her positioning.
In this guide, I will try to show you guys how to use her Q (Bladesurge) to it's fullest potential and just typical plays, laning, and positioning as Irelia.
I don't intend on this to be complete and indept guide, just some general tips and tricks to Irelia

If you are an advance user, just skip down to the chapter call "Mechanics with Bladesurge"

Credibility: http://www.lolking.net/summoner/na/27794257
..and no, there will be no pretty pictures or cool fonts to make it easy on your eyes.
Only softies need those, we haven't got time to do that. We gonna get straight down to the facts and mechanics like REAL PROs do.

Pros
Good sustain
Kit is perfect for diving enemy carries
True damage
Win a lot of lane match ups
High mobility
A true bruiser

Cons
Very item dependent
Not useful in the wrong hands
'Lack of means to escape'
Single target dps.

For the way I play Irelia, I start with 2 wards, 6 health pots, and 3 mana pots.
CS until you're out of potions.
Buy a sheen.
IF YOU CANNOT AFFORD SHEEN ON A SINGLE PURCHASE
Buy cost efficent items such as Dorans shield, long sword, or ruby crystal to help you sustain better for csing.

-Come back to lane with a ward or two; focus on finishing your Triforce and Guardian Angel.

I can't tell you exactly what items to build because every game/lane match up is different, instead I just dropped a few items I love to buy when playing her and hope it is suffice for you readers.

Core items:
*Triforce - Health, mana, AP, sheen procs, phage slows, attack/movement speed all benefit Irelia exceptionally.
*Guardian Angel - Extra resistance and second life. To kill the carry :D!
*Randuin's Omen - Extra health and armor. Active can allow Irelia stick to the enemy carry despite peels. The Warden mail passive allows you to win 1v1s against the ADC.
*Witt's end - Hiten's style (w) grants Irelia true damage along with auto attack. Witts end passively gives bonus attack speed and 42 magic damage per attack. Also stacking magic resist per auto.
*Boots - doesn't really matter what boots you buy, I like to run the boots against whoever I'm against in lane; if AD heavy, buy tabi. If high magic/cc, buy mercs. I like homeguard on Irelia because when she moves fast, she looks funny ^-^.
You can also run Captain or Furor instead of homeguard.
Here are the circumstances for the enchantments:

Homeguard, if you are missing a few tier 1 or 2 towers
Captain, if you are the main tank, initiator of the team
Furor, usually good because Irelia has so many single target spells

*Runic Bulwark - If your support does not buy a bulwark, it's always a good idea to buy one as Irelia. Extra armor and magic resist are always welcome.
*Banshee's Veil - Passive allows you to block one negative spells. When you're initiating a fight, this could be really helpful along with your 40% Tenacity from your passive and an extra 15% from masteries.
*Spirit Visage - Good MR item, it's passive grants you bonus heal from your hiten style and lower cooldown, and a good bit of health. Not really recommended unless it goes really late game or if the enemy has high magic damage.

Depending on the rest of the enemy team, choose from the item list above.

Against squishy targets, start Bladesurge. If you are matched against a melee bruiser, start E.
Focus on farming, as Irelia, you are one of the most item dependent champions in the game.
Thats why you don't jungle Irelia, no $$ = :(

It is very possible to have perfect CS with Irelia and do able. (although I've come close many times, I've never managed to.)

As soon as both minion wave meet in the middle of the lane, drop a ward in the river.
This will give you visibility of incoming ganks. Knowing is half the battle, and you just won half of the laning phase. ;D!

Learn to freeze the lane.
Keep the enemy minions and your minions number the same, but further to your side of the lane. If your enemy wants to cs, they would have to over extend and put themselves in severe risk.

Typical csing mechanics but I'll review them.
Melee minions can take 2 tier 1 towers before falling to one auto/bladesurge
Caster minions can take one tower shot before falling to one of your autos with W proc active; at higher level, or with a sheen/tri force you can use bladesurge

There are a few champions that has kits just perfect for countering Irelia. (circumstances depends)
They are:

Ignite/healing debuffs. Irelia excels at trading because of her ability to heal after every auto or Transcendent blade (r) cast. It's also where her sustain comes from. If you are against an Irelia, I suggest ignite as one of your summoners.

Malphite. Malphite's E is an attack speed debuff; Irelia's damage comes from her W procs with autoattacks. Rock beats blades?

Olaf. This crazy axehole will win every trade against most melee bruisers with his E. True damage OP.

Jax. Like Irelia, Jax's damage comes from his autos with his Q being a high range gap closer. What makes Jax better than Irelia is his E. With his E active, he is able to dodge your autoattacks (even with w active) and stun you in return.

Just because you got counterpicked doesn't mean you can't win the game. Irelia scales better than all these champions late game. Yes, even Jax. You have one thing Jax doesn't. Build in Tenacity from your passive and masteries. Best way to win the lane is just by outfarming them. You outscale malphite and you definitely outscaled post nerf Olaf.

Irelia's Bladesurge, in my opinion, is one of the best skills in the game. It gives her very high mobility and means to CS.

So, how does bladesurge work?
Bladesurge is a gap closer with a 650 range (enough to catch a Caitlyn at her max auto distance range). If landing bladesurge gives the killing blow, the cooldown is instantly refreshed and is available to use again with half the mana cost refunded to you.

...So? Not all that impressive.
Not at first, but isn't that what this guide is for?

So, why not max Bladesurge first? More DMG, lower cooldowns!
Yes, at higher ranks Bladesurge gives a lower cooldown and much more damage but the mana cost is higher. If you max Q in laning phase and you auto minions, your mana bar will plummet before you have a chance to trade with the enemy. Remember, only HALF is refunded.
Besides, a well played Bladesurge Irelia will have virtually NO bladesurge cooldowns.

I'm oom. Why?
You boob, stop using Q for all your csing. Don't need to Q for the kill if you can auto.

Stunning.
Bladesurge (q) to minion that is almost dead near the enemy champion and use your Equilibrium strike (e) on the enemy.
Because you didn't damage the enemy with your q, 2 things has happened.
1. your Bladesurge (q) is off cooldoown and ready to use for an escape or pursue.
2. your enemy is stun because you did not damage them with your Bladesurge (q) and assuming you were both full at health and this is your first time trading.
If your enemy is not stunned, they are slow, this still gives you time to continually harass with your hiten style (w) activated.
Video:
Play Video


Instant Gap closer.
Bladesurge (q) to a low health minion between the enemy and you and because your Bladesurge (q) gives you a cooldown, you can either Q again or flash to land your Equilibrium strike (e)
If you..
a. Flash, make sure it's a kill. I hate wasting a 300 second cooldown.
b. Bladesurge, do as much damage as possible with your Hiten style (w)
Video:
Play Video

under work. be up soon.

My inspiration was mainly from watching Wickd from Evil Genius playing Irelia.
This is my first actual guide.
I play on the NA server, ign: Idiot
My best lane is Top lane, my favorite champions are Singed and Irelia.
Because Singed became my go-to champion to win ranked games.
I am currently in Platinum V.

If you have any comments/questions/hate, add me ingame or find me at jeaybeat@hotmail.com.

Hope this guide was helpful
Depending on how good this guide turns out, I may do a guide on Singed guide