The greatest potential for going from 25,000g to the gold cap of 214748g is transferring servers. However, this also presents the greatest risk and needs the most preparation. First off, transferring costs money. If you go to a server, transferring back as soon as the cool down is up is expensive and impractical. You should look for a server that you can stay on for at least 6 months to a year before transferring back with your huge profit. However, the maximum amount of gold that a max character can transfer is only 20,000. Therefore, you need to purchase goods that are going to net you the most profit when you go to sell them on the new server's auction house. Primarily, these are enchanting mats, but can also be BoE epics depending on the two servers. Before making a risky decision such as transferring, consult the questions below.
Finding the best route for you can be a bit tricky because of the size of the dungeon. I will usually only do about half the dungeon, killing as many mobs as I can in 6 minutes. After 5 minutes, make a group in the group finder and leave it. That will leave you a minute to complete your 6 minutes and you will be ported out on the 6 minute mark, ready to reset and port right back in.
If you already have a high level character or a friend willing to give you gold then you can purchase Heirloom items. These items are bound to account and are accessible through the Heirlooms tab using Shift+P. The benefits of these Heirloom items is that they scale with your level keeping your gear up to date without you having to worry about upgrades, and they provide a significant XP bonus.
Once your character makes it to Outland and beyond, cashflow frees up considerably. The quest rewards are much better than in Azeroth. In fact, a typical character will earn from 1000-1200 in quest rewards and vendor trash while leveling 60-70 in Outland, and perhaps 1400-1600 from 70-80 in Northrend. The tendency is, therefore, to spend more freely after one hits 60. However, it is important for players not to go crazy on their spending once they make it to Hellfire. One thing is, training costs, repair costs, and consumable costs are also higher. More important, there is a large purchase that you are going to want to make at some point after level 60, your first flying mount and skill. The "bird" costs 40, the skill will cost you far more. Not only that, but if you want to fly it in Northrend at level 70, you'll have to shell out another 400 for Cold Weather Flying. And for those characters who will be 'farming' herbs or ore in either Outland or Northrend, an elite flying mount is almost essential, as it helps you gather almost twice as fast. That's another 5000 you'll be looking at. Therefore, budgeting carefully during the 60-80 leveling process is essential to ensuring you have sufficient cash on hand for making those purchases. Saving your pennies early makes that bird appear that much sooner.
Level with a pet if you can because it will help keep you safe. If your pet is tanking all of the damage from the enemies you’re fighting, you won’t have to. The other reason is that pets are easier and cheaper to heal than you are. If you don’t have a pet, make sure you know how to use your defensive abilities. You can’t level quickly if you are dying all the time.
The problem with Battle for Azeroth’s endgame is that a culling of abilities, the loss of Legion’s legendaries, and a lack of endgame talents means that hitting the max level doesn’t necessarily make your character more fun to play. Your character is a vehicle to explore new content, and it doesn’t matter how stunning the vista is if the core gameplay loop you’ll execute a few thousand times just isn’t fun.
No he's just not paying attention. The wanted quests are built into both the leveling guides and the "Zandalar Forever" achievement guide. They aren't in the rep guide because they are not repeatable and by the time you hit max level they should be done. You'll also notice the rep guide doesn't contain every single possible completable quest that rewards rep. It is designed to focus on repeatable objectives, world quests, large quest lines, and missions.