For those interested in more details on spending wisely, and generating good cashflow, we cover a number of topics in more detail. Please note that this guide represents the accumulated wisdom of many people. You don't necessarily have to do all of these things--there is no one "right" way to make and manage money. However, these pointers will give you ideas on how to establish a firm financial foundation for your character.
I made some route changes to the Horde levels 43-44 sections.  I have swapped 44 Dustwallow Marsh with 44 Desolace (the entire sections). This allowed me to do Deadmire (at lvl 43 instead of 38) and then go stop at TB to turn in Deadmire + The Black Shield at the same time, then fly quickly to do the Desolace stuff.  Doing 44 Desolace is now mandatory because I think its faster with the new routes. This will also make the level 53 grind much shorter.  I think these were great changes.
As the battle for Darkshore begins, both the Alliance and Horde are blindsided by a new development: High Overlord Saurfang, who had been defeated and captured in the Battle of Lordearon, has suddenly escaped Alliance captivity and is on the run. Sylvanas sends Horde Champions to track Saurfang down, ostensibly to extract him. However, it quickly becomes apparent that the search party is in fact an assassination squad, as Sylvanas suspects Saurfang of colluding with the Alliance in an attempt to dethrone her. While some Horde champions choose to side with Saurfang and help him escape the assassins, other champions remain loyal to Sylvanas and report Saurfang's and the dissenting champions' treachery to her.
I think you are referring to the Env Bert strat I have linked. Basically I agree. But you might have noticed that I already had added min power to pet #2, in order to exclude some of the substitutes. Though, I didn’t wan’t to do the same with the Blazehaound (pet #1), because I think the strat is doable also with a suboptimal breed. But maybe you are right and I should just exclude any non-P/P breeds.

The same goes for the level 40 mount. An elite ground mount means still-faster leveling. Not only that, but you'll get knocked off considerably less often by mobs while getting around inside zones, meaning you'll die less often as well. Remember, as the goblins are so fond of saying, "Time is money, friend!" So it behooves you to get an elite ground mount as rapidly as possible.

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Back in the days of Burning Crusade, leveling up your character was a very tedious procedure. The quests were not even shown on the map, you always had to read through the quest list and figure out where to go and what to do (which mobs to kill, items to retrieve, etc.). After a few more expansions, questing became a little bit easier, due to the quest chains being more linear. You can pretty much follow the main quest storyline. Also, the map became more interactive.

And if you decide you need to go back to an early zone to get low level minerals or herbs? Instead of meekly wandering around ignoring you to gather in peace, now the local mobs are the same as you again and aggro on you. So you have to fight your way in and out. Same spell rotation, over and over and over. 31373433. 31373433. 31373433. 31373433. 31373433. 31373433. Every combat the same. Over and over again. Never ending. No change. Mind numbing. No challenge.
While leveling, try to make use of the new Battle of Azeroth experience gem, Insightful Rubellite, which gives you +5% experience. Equipping one of these requires a socket in your gear, so try to hold on to a piece of Legion gear with a socket or acquire one of the Legion Legendary rings since every class has one. Each of the rings includes a socket. You can acquire one of these rings rather easily by doing World Quests in Legion zones and acquiring 1,000 Wakening Essences that can be used to purchase a legendary ring in the Legion version of Dalaran.
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.