Well, this is my first guide so i hope you won't judge me to hard.^^
Feel free to comment about this guide I'd like to know what you guys think about it.

Well, ghost and flash. I think Ezreal is so squishy that you just need
these 2 spells because they give you great survivability.

Ghost is really good to get to another location really quick or to chase other players.

Flash is just the best spell to not get ganked by a jungler.

You might take ignite to have a better early game but yeah i prefer ghost and flash.

I think these runes are the best but here are other possibilities:

Red : Armor Penetration. You should keep those.
Yellow : Mana Reg per lvl/Dodge/Flat Armor.
Mana reg runes are useless in endgame with this item build they could
help you a bit at the start but I prefer dodge runes.
Blue: Magic Resist/CD Reduction.
Quints: Armor pen/HP.

Ok some of you may think this item build is totally useless but I swear you, it isn't.^^
Test it, it's really good!

You have a great amount of Mana which allows you to spam skills and you
get more Attack dmg the more Mana you have because of Manamune.

I personally think that Mercury Treads are the best boots in the game.
You can buy other boots, but the -35% of all effects is so useful that you should have it.

Trinity Force is pretty cool but u could get other items instead of it, but the movement,the effects and the + mana from sheen are really good

Your 6th item depends on how the game is going so far. sometimes a guardian angel is good, sometimes a bloodthirster, etc...

Banshee's Veil is a must have i think. You get more Mana = more dmg from manamune and you cant get stunned once every (30)? seconds i think :P. A stunned Ezreal is instead dead therefore it helps a lot.^^

If you have an enemy team full of attack damagers you can get frozen heart. it grants you more Mana = more dmg, more armor and if they attack you they get slowed so its a great item.

Sooo.

It would be best if you go and solo in mid.
You should get Tear of the goddess as soon as you can and after you have it you
should always increase your mana so you get more dmg later on from manamune.
ALWAYS try to last hit creeps, I personally think that the early game creep kills are more important than a few hero kills!
Do NOT play to offensive, I often see ezreals who use their E skill to damage the enemy on a lane and then they get ganked because the skill is on cooldown and then they are pretty much ****ed^^.
Always try t haor*** your enemy with your Q skill, but you can also greatly use it to last hit creeps.
as soon as u hit level 6, always check the map or make sure that your teammates inform you about low hp enemies, because you could snipe them with your ulti.
You can switch your lane very fast because of ghost and your E-skill so make sure you take advantage of that and gank sometimes.

Kiting:
Ezreal is good at kiting.
Example: Bot lane. You and your mate and 1 enemy

The enemy chases you but you just run away, he will realize that he won't get you so he changes hit target and starts hitting your teammate. So you start hitting the enemy again, he knows that your an easier target than your teammate and starts chasing you again, but you just use your E-skill or flash to get away. In all the time your running away, your teammate has enough time to keep hitting the enemy. And as soon as your opponent is on low hp you kill him :).

Positioning:
In team battles, positioning is the most important. Many carries just run in and attack the enemies, they get focused and they are instantly killed. Thats not what you want.. So make sure your E-skill and flash are not on cooldown before attacking. Position yourself behind tanks or try to attack their casters from behind. NEVER initiate a battle.^^ always try to kite enemies in fights because all your teammates can attack the on chasing you.

Pros:
very good farming.
good at harassing.
Good survivability due to E-skill, flash and ghost.
Skillshots
Kiting!

Cons:
Very Squishy at the beginning, stun = your death.
Always have to care not to get focused in battles, but yeah thats the carry role.
Low dmg in earlygame, but good in mid/late.

Well yeah that was it from me :D

I hope you somehow enjoyed it ^^ have fun testing it.

If you don't like my english, I dont care :D im german and i think its not even that bad. :)

Muftaay!