The World of Warcraft API has a list of functions that you can interact with and to talk with WoW using Lua. These are your building blocks for manipulating WoW windows and chat boxes and so forth. Looking at these for the first time can be very daunting. But don't be discouraged. After getting more familiar with Lua the WoW API gets much easier, and the documentation gets much easier to read. Keep in mind there are many different ways to accomplish your goals, so when going though the API keep looking until you find a way that best suits what you need.
Also note that power leveling is sometimes used to refer to paying someone else to level your character to cap as fast as possible (i.e. they power level for you); a distinction used by Blizzard is to refer to the paid leveling as "power leveling service." This behavior is against Blizzard's Terms of Service. Power leveling yourself, which this article covers, is perfectly acceptable.
I used to use his profession guides they really did help in the pre cata days (before WoW professions site was around) It's really up to you he does keeps his guides up to date and he does he homework (I still get emails) Their are some free leveling power leveling add ons to help you level much like the paid guides. Keep im mind I think he moved to a sub based plan and not a one time payment
If you're looking for simple, just get actionator. Set it to undercut everything you post for 1c and alt click from your bags. It will place the item on the ah window, do a scan for that item and autoset the price for how much you told to undercut (you can change it accordingly if you feel like it). It will remember if you do stacks for which items and replicate it everytime.
Arms: Sharpen Blade - When activated, your next Mortal Strike will deal 15% increased damage and reduce healing taken by 50% for 6 sec. Fury: Battle Trance - You go into a trance causing you to regenerate 3% of your health and generate 5 Rage every 3 sec for 18 sec after using Raging Blow twice in a row on a target. Using Raging Blow on a new target will cancel this effect. Protection: Thunderstruck - Thunder Clap roots all targets for 1 sec. Tuning
Holy: Divine Favor - Your next Holy Light or Flash of Light is increased by 100%, costs no mana and is unable to be interrupted. Protection: Steed of Glory - Your Divine Steed lasts for an additional 2 sec. While active you become immune to movement impairing effects, and you knock back enemies that you move through. Retribution: Unbound Freedom - Blessing of Freedom also increases movement speed by 30%. Priest
Excess Potion of Accelerated Learning: Acquired in your Garrison (part of the Warlords of Draenor expansion), this gives you a 20-percent bonus to experience from killing monsters and finishing quests. It lasts one hour, but you can buy it multiple times and use it back-to-back. Alliance players buy it from Sergeant Crowler, horde players buy it from Sergeant Grimjaw. Does not work above level 99.
Another part I like about Dugi’s leveling guide is the ease of use. You’ll be given the guide in different forms so that you can find the one that fits you. For those that like to have a printed guide alongside them he provides you with a printable and image heavy version of the guide. A very powerful system Dugi uses is his in-game leveling addon that permits you to play without having to take your focus with the game itself. The addon adds a tiny window for your World of Warcraft game that tells you what area of the guide you’re at and how to proceed next.