FYI: If you’re returning to WoW after an extended absence prior to patch 5.0.1, it’s possible that you’ll have more than the maximum pet limit and/or more than 3 of a kind. However, this will be the only time that you’re allowed to surpass these limits. You will have to pare down your collection, eliminating your duplicates, in order to add new pets.
Through out the game, the quest log will be capped to 20 many times.  The guide makes use of maximizing the total amount of quests you can accept at once.  Because of this it is important to follow the guide exactly and only accept quests if the guide tells you to so you won't run into issues not being able to accept a quest.  If you do accept a quest that is not listed in the guide, write it down because you may need to abandon it in order to keep following the guide if your quest log is full.

When hovering over an ability, the tooltip will tell you whether or not that attack is weak or strong against certain pet types. Additionally, you can hover over the opposing team's pets and view their attacks during combat. This will be important since it’s a good idea to pit a pet that's strong against the opponent's pet who's vulnerable to that type.
Some even more advanced gold makers might also attempt to monopolize the market. It’s fairly easy if you have quite a bit of gold – just buy out every single item on which you want to have a monopoly on and then reintroduce it to the auction house with your new (and higher) price. However, it’s worth mentioning that monopolization tactic is risky business practice. But where’s high risk – there’s high profit.
The leveling guides on my site are essentially speed leveling guides.  My leveling guides are the same guides I use myself to speedrun to 60 on new servers to get 60 server first.  I list many occasions where I tell the player to "die on purpose" to go faster.  I tell the player to skip certain quests, because some quests are just not worth the time/XP.  I list tricks and shortcuts to go faster so you can reach level 60 much quicker.  I am still constantly going through them over and over again perfecting the guides to make them faster and easier to follow.  For the most part, the guide can be followed without the need from other player's help, as the whole guide was made from a solo run anyways.  Although I do list quests that can optionally be done if you have a group.
This is something that people really need to start to understand, not just for Classic or WoW but software developement in general. Fixing a bug isn't just flipping a switch or changing a single digit. You have a machine with literally hundreds of thousands of parts, designed by dozens of different people at different times over the course of 20 and more years. You change a single thing and it might break 50 other things in very subtle ways that might not even emerge until months later (i.e. the very high M+ keys some players got at the start of BfA).