World of Warcraft offers a lot of ways to make money (gold). There is no one "right" way to make money, although there are some definite wrong ways! Some people like to play the Auction House, some people do their daily quests, some people tend to farm, etc. Many characters do a combination of all three of these along with other activities. Below is a compendium of money-making methods.

Cool the whlelping spot that has caused so much controversy int he gold farming community.  I still think spot is mentionable because it's really the only reliable spot to pull out a crimson whelping.  Most of you are probablly thinking this farm is old and beat to death, and you are right.  BUT that does not take away the fact that the whelping does drop highest from this farm.  If you can get it from the slavemasters your looking at anywhere from 25,000g and above.  A cool nifty old spot, that has survived the test of time.
This new farm takes advantage of the level scaling changes implemented by blizzard.  Event NPC's like the NPC's found in the twilight outpost, scale up or down depending on your level. HOWEVER, your level also determines which loot tables each mob will have.  By using a level 58 character, you can successfully loot items in the 57 – 59 item range, a range which has some of the most expensive and well sought after transmog items in the game.  In less than 30 minutes farming this spot I was able to snatch up some glorious legplates[/URL] (on video) – worth a stunning 150,000g.  Watch the video for absolute details I suppose, but the gist of it is you need to create a level 58 DK, go to the twilight camps, and start the killin'.  Unlike before, an implementation of a daily event has changed the loot tables!   This spot is the new hot thing on the block.
Zygor Leveling Guide is aimed at improving your playing experience. It is a known fact that trying to figure out your next move can be quite frustrating. Also, you spend lots of time and effort just thinking of the next approach. Zygor Guides takes away the frustration by guiding you through the gaming experience. It gives you the option of pursuing the endgame in a more relaxed manner, or at neck-breaking speeds. Reaching 90 will take you less than 7 days. This is usually a tall order even for experienced gamers who aren’t using guides. The step-by-step guidelines will also ensure that you will still remember the moves you made.
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.