Battle for Azeroth’s War Mode puts you into PvP mode and grants you 10 percent extra experience. But since the two factions will mostly level in separate zones entirely, you should almost definitely have this on when you’re leveling. That said, if you start getting killed by random PvP players consistently, stop using it. Although 10 percent is nice, it’s not worth dying every few minutes for.
Island Expeditions are three-man scenarios that pit the team against three enemies using what Blizzard calls “advanced A.I.” That means the enemies will act more like players, pursuing goals proactively and filling class roles. The expeditions take inspiration from action RPGs, with randomized areas that mix up the experience each time. Players’ main goal will be obtaining resources more quickly than their foes, and expeditions should last 15 to 20 minutes. While primarily meant for PvE, there is a PvP mode that replaces the opposing A.I. with teams from the enemy faction.
If there would be a transmog server #1, all transmog vendors would transfer there and the market would get destroyed fairly quick. In general, Roleplay-Servers like Argent Dawn or The Aldor are better server for selling transmog. On high pop servers you have a lot of other players selling stuff and as a result, low prices. On low pop servers prices are acceptable, but you have no buyers. So there is not recommendation for a server really. Its up to you.
Nearly all quests offer cash or items as a reward, and often both. While completing quests shouldn't be your main form of wealth generation, it is something you are going to do anyway. The key to making the most of quests is picking your reward items wisely. Don't always pick the item that most fits your class - if it isn't demonstrably better than your current item, instead go for whatever reward sells for the greatest amount to the vendor. You can select the in-game interface option to display it in the tooltip. In general, if you can't use a quest reward for your character, pick either a plate-armor or melee weapon as your reward--these tend to sell to vendors for more than other items.
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