Ahri tips?

Some lesser known ones.

You can flash during the channel of your charm, causing it to have no delay on cast once you've flashed. (So E+immediately flash)

Her orb gives movespeed, so when leaving base fire the orb backward. You're mana will regen in the short time you are running out of the fountain and you will get a slight movespeed boost that will make getting to lane a bit quicker.

Her orb will still come back even if you die, and you can also flash/ult/etc in order to change the orbs curve. So if a person dodges your orb, you could still ult to their side so that the orb comes back and hits them.

Prevent tilt. Ban Yasuo.

Max W. Wait for level 6. Click W, Click R, R again, R again. 100% killed an enemy. If you want to make it harder for yourself. Max Q and try the E Q W combo. You may like that style better. But my first suggestion is better. U can OS nearly everyone at level 6 without any sort of aiming or anything that way.

So watch Faker :)

Your item builds look good, but consider getting if your first item is not , and the enemy team is not MR-heavy (or has so much MR that 15 flat pen is useless vs sustained damage). The rest is really just practice. A few mechanical tips (you have probably seen these already): Try to hit targets at the very end of your Q range when they are going to CS, making it hard for them to dodge both hits. Wait slightly before using spells after a dash, people often panic-trigger any dashes, flash or defensive abilities if something suddenly zooms at them. Wait half a second until you can tell where they are going. Mindgame people with spirit rush. 10 seconds is a long time in a team fight, people will often forget that you have one charge left. Use spirit rush. It has a really short cooldown, especially if you max CDR (you should). Just use it any time someone is out of place. Ward, and get a blue trinket if nobody else has one. Spirit rush is great for ambushing people over walls and retreating safely.

Some situational items i have found useful: Very late-game item, after deathcap, the turret siege ability it gives you allows you to splitpush and the movespeed is very useful. Also great for kiting damage, as spirit rush triggers spellblade. If you stagger spirit rush, you can be looking at an extra 1500-2000 magic damage over the course of a duel. Veigar and shit like that. Your DPS is 0 when dead, so this is a great damage-boosting item. I hear this is good, but have never really used it. Just another dash to mindgame people with. If you reach a point where you can sell boots and get a 6th item, it should be ludens or lichbane, in that order, as the movespeed loss will be small.

Stuff you should never even think about building, no matter what anyone says:

Also try ADC ahri at some point, it is hilarious and strangely effective.