There are 5 Dreaming whelps and 7 adolescent whelps spawns, They drop the small flame sack which sells for a decent amount at auction house or can be used to make fire protection potions. The sacks have around 10% chance to drop and it's one of the main reasons you want to grind here. On top of this you'll get lots of grey items, green and blues with a higher chance than your average mob. If you are not aware yet, dragonkins have the best loot table in the game while having less HP and armor... making them easier to kill, assuming you're not fighting elites...
Jadefire Betrayers, Hellcallers, and Tricksters (marked RED on the map) - These foul Satyrs infest north-western part of Felwood. Slaying them will help Druids reclaim Felwood, and provide you with a lot of Gold. These Satyrs drop a lot of Runecloth, Felcloth (the main source of income from this spot, check the AH prices), 16 Slot Bags, Vendor Trash Items, and some Pocket Money. Satyrs can be Pickpocketed, so this spot is especially good for Rogues. Recommended Level - 52+ (54+ to be extra safe, as Satyrs can be problematic because they tend to run away on low health and pull additional enemies).
There are more passive methods to gain wow classic gold, but these are slower. For example, many people choose to fish in places like Tanaris, or kill Harpies in Feralas and loot items such as mageweaves. These are rather AFK-able, but again, not as rewarding. Some people choose to favour fun over anything, and like in any MMO (massively multiplayer online game), the best way to have fun is playing games with friends or your guild. Dungeon runs with your friends provide social interaction and are definitely helpful over the long-term for your gold stack!
Some quests in my guide are marked as "SKIP" and colored in red. These quests are simply either too hard to solo or not worth the XP/time and are skipped. My guide will only list SKIPPED quests if the quest is a direct follow up after completing a quest, not one that you have to click the NPC again to get it. If you hover over the skipped quests, it will give info on why it is skipped in the guide (unless that info is already listed directly in the guide text).