This is where I will let you know about all of the updates that I do to this build.

[5/8/13] Posted Ahri Build.

Future Updates

[6-7/8/13] I will get some screenshots of a game I play with and without this build to show you the difference it makes in my game.
This isn't my first build - but rather archived the old ones and re-done the ones I have previously done to make them better.
This is the way that I play Ahri so don't judge me on that. I'm willing to look into better suggestions for items and such, but don't be rude about it. I don't claim to be one of the best with her - I have my good games and my bad games of course, like we all do.
AP runes are where it's at for Ahri (This can probably be used for other AP champions too - I just haven't tried it). I mean have you ever seen an AD Ahri? No need for anything that relates to AD whatsoever.

Greater Mark of Knowledge - This rune is great for mana gained per level. 21.06 extra mana by level 18 which is needed due to Ahri being mana hungry for the first several levels. Plus it helps when there's a team fight going on and the Orb of Deception has to come out many times along with Fox Fire.

Greater Glyph of Potency - 1.2 Ability power. Very handy if you want to build an OP/AP Ahri to the point where the enemy team wants to surrender. This helps especially at the beginning of the game where you need the AP to lay down some damage.

Greater Quint of Replenishment - +1.25 mana regen per 5 seconds can come in handy, especially early game again when Ahri wasnts to be mana hungry because you're blatantly trying to get the kill that someone else wants to gank on.

Greater Seal of Force - +0.1 AP per level, which may not seem much but when you start off with no AP at the beginning of the game because of boots and potions, this can help you lay that damage.

If you're thinking about using any other runes for Ahri make sure that you choose runes which involves mana regen, some AP and/or possibly health/survivanility.
You mainly want to focus on your Orb of Deception and Fox Fire due to Charm being the main thing to lure them in. Your first to skills basically mean that you can lay damage on them whilst Charm is in action.
Try not to hit minions with your orb when you use your Q when attacking an enemy as you're trying to focus them and not the minions.
As for your ult, when you use it on an enemy also incorporate Fox Fire as they both target the enemy champs.
Use Charm to check bushes rather than face-checking them and dying.
Charm can also help you to get away if you're being attacked by a melee champ. It slows them and stops them from attacking you all together so you have an extra second or two to get away.
If you need to, get the blue buff to help you with your mana issues.
If you're solo mid, get two sight wards and place them one on each side of the river in the bushes. Easily forseen gank. Top or bot, place a ward in the bush at the end of the river. Again, easily forseen gank.