Since you’ll already have to complete quite a few World Quests to reach the required reputation levels for the previous achievement, this one should come naturally. It’s worth noting that this achievement specifically requires 100 different World Quests, so if a World Quest pops up that you don’t recall having done before, it’s best to head out and knock it off. Completing "Beachhead" 100 times just won’t cut it, but Scrollsage Nola certainly appreciates your efforts.
Most of the players make the mistake of only listing 30-50 transmog items on the auction house and then hoping to get half of them sold until the next day. Me and a lot of other gold farmers and transmog sellers do have 3.000-10.000 items on the auction house across various realms. It does not mean you have to do it that way – but if you have 1000 items listed, chances are higher you can sell up to 10 per day. With only 100 items listed, you have to be lucky to sell one. Of course, the sells are not guaranteed if you post more items. But i’m sure you have a lot more fun if you open your mailbox and 10-20 items are sold