Hey
My Name is Akropon, I am playing on EU west and Orianna is one of my most favorite Champions

I am Currently at around 1720 elo
Here u have a picture of my profile

Pros :

• Can Lane against everyone
• Great utility for the whole team
• Good burst
• One of the best Ults ingame

Cons :

• Hard to play
• No dash or jump to escape
• Short range

Here you have quiet abit of options.

Marks: You should take Magic Penetration marks, as they are offering a good amount of magic pen and there is no other viable option.

Glyphs: Here you can get Glyph of Magic Resist or Glyph of Ability Power. I prefere playing Glyph of Magic Resist, cause your goal should be farming up and wait for the midgame. But in a really easy matchup you might could go for Glyph of Ability Power to get some more early damage.

Seals: Seal of Mana Regeneration if you are against standard AP mid. If u are vs someone with heavy ad damage such as Pantheon, get Seal of Armor.

Quints: Quint of Ability Power is allowing you to trade with your lane Opponent.
Just a little bit more damage. You can go for Quint of Movement Speed to dodge skillshots and running away from ganks. Just try out and take what you prefere.

21/0/9 is pretty standard for AP mid offering the best amount of damage and utility.
When u are against AD mid such as Pantheon or Talon run 21/9/0 going for armor and life.

Max Command: Attack for the damage it offeres and the early game harras.
Take Command: Dissonance second for the damage and slow.
As 3th Command: Protect, it is an awesome spell but not worth maxing it (you aren't playing support).
And take Command: Shockwave whenever you can.

Command: Attack:
Always get this on lvl 1 and leave it in the Brush in the river so u don't have to stand there.
You can and should always use it for brushcheking.
It is your main harras skill and you should try to master it, since it is the most important.

Command: Dissonance:
Awesome spell. The slow and speed up can be really usefull. When u have a tank you alawys want to e+w him so he can initiate better in the teamfights. If u don't have your e ready just q+w to speed him up.

Command: Protect:
The shield is really nice to win trades in lane. Don't forget it does damage when it travels threw enemeys. When it is lategame u should always e the tank so your Balls is closer to the enemys, since you aren't gonna stand in atack range.

Command: Shockwave:
Makes or breaks an Orianna Player. You have to train that spell alot and learn to time it right. When u land it on 4 enemys in a good situation and you are well in build the fight is won. Don't panic and do it right away! Wait for a good situation. If you have someone like Malphite / Amumu or Maokai e them and than wait them to jump into the enemys. Mostly you can always land a perfect then.

Since Orianna has no hard counters you can just firstpick her if you want to. There is no "**** i lost" matchup.

Clockwork Windup is helping you alot here. You should not have too much problems Last hitting. Try to be somewhat around 80 at 10mins.

Get Boots and Health Potion x3 as starting items.
Try to get 1000g before going back to base. Grab Chalice of Harmony and a sight ward.
Rush Athene's Unholy Grail and then get Sorcerer's Shoes again dont forget to pick up 1-2 sight ward's.
on 22-26mins you should have your Rabadon's Deathcap.
now you should go for Void Staff and Zhonya's Hourglass.
Last item Guardian Angel

This is a Video of one of my favorite Orianna Players
Just watch his Gameplay, you can learn alot from it.

Thank you for reading my Guide, if you have specific Questions you can add me ingame and just ask. Please make sure to leave a comment and tell me what i can make better :)