This guide is based on Akali - Ready and Willing. I made this build just to show you my favorite build and not to challenge any other builds.
I'm not much of a guide-maker-person so for now this will be a short guide. There's a slight chance that I might update this to a real guide though. Most if it might probably still be based on the guide mentioned above, but with a twist from me. Stay tuned.

I sometimes switch the order of some items depending on the situation. What I do try to do is at least to buy the Sword of the Occult and the Mercury's Treads before moving on.
Then I sometimes buy Hextech Gunblade first and sometimes Rylai's Crystal Scepter. It's even possible that I mix them up.
If I make it this far the next items is most dependent of the game. I haven't tried using these items much, but I don't think Guardian Angel is necessary. I added it just in case I later find out it's really helpful.

When building masteries I have complete focus on offense until it's filled. I aim to get Archmage's Savvy and Brute Force as fast as possible to help improve Twin Disciples.
If you follow this and the rune build below you can activate Akalis Spell Vamp at level 1 when you're summoner's at level 20.

With my rune build both of Akalis Twin Disciplines will surely be activated at level 1 when you're summoner's at level 30.
If you're summoner's at level 20 and you're following my masteries build you can get the following Tier 3 runes to activate Akalis Spell Vamp at level 1. I recommend you to do this.

• 5 Greater Mark of Strength
• 1 Greater Mark of Potency
• 4 Greater Seal of Strength
• 2 Greater Seal of Potency
• 2 Greater Glyph of Strength
• 4 Greater Glyph of Potency
• 2 Greater Quintessence of Potency