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.
The Horde 12-20 (Barrens + Stonetalon Mountains) guide has been rewritten and revamped. In addition, there has been numerous tweaks to the speedrun route to make things faster and easier to follow. Also, in case you haven't noticed I am now adding about 40% more info per step and redoing all the images. Unlike with my previous vanilla guides, I am now giving a brief explanation of where to go and what to do with each step along with any other helpful tips.
Only really to expand on Gráinne's comment as regards the 'collecting' and 'roster development' sections - which are, as said 'distinct' although they are intrinsically linked - I would like to point you in the direction of the in-game Achievements > Battle Pets > Collect tab. There are a series of achievements called Raiding With Leashes, pretty much all of which can be completed via the auction house - if you have the gold/inclination - or by completing old raids.
You create a meta where you're constantly buying gold. Gold is very important in vanilla consumables are the difference between being a hardcore raider and being a casual. The notion that wow token doesn't create inflation is incorrect. By giving every player the ability to buy gold you're increasing how much gold your average player will have. the 1% rich player who has the ingame gold to buy these tokens was not trading with that gold. But now they buy ingame time and the gold that was sitting in their pocket is now being used to trade, buy items, herbs, etc. now there's more gold in circulation. Now everything costs a little bit more gold. And if you're a player who's not buying wow tokens with real life money you have to farm just a little bit longer to compete. That's why wow token is bad.