Gadgetzan Farming in wow classic

Kill Wastewander and Southsea monsters over and over again to increase your Reputation. Also, you can do quests that can be found in Tanaris. If you are Hated, you can as well do repeatable quest up until neutral.

Ratchet

It’s a faction Found near The Barrens in Kalimdor. It is a place where Horde can traverse into the Alliance territory, as Ratchet is connected with Booty Bay by a ferry that arrives here and there from time to time.
Ratchet Farming

To reach Exalted status with these mad-lads, you will have to do quests in The Barrens and Desolace. And as with every town under Steamwheedle Cartel’s custody – they are not only non-hostile towards both Factions. They will also allow you to repair a broken bond offering you a repeatable quest that you will be able to do over and over again to reach Neutral status with this Faction.

Syndicate

A criminal organization led mainly by Humans, who plot together to expand their territory and influence others. The group resides in Arathi Highlands and Alterac Mountains, with some small outposts in Hillsbrad Foothills. They are currently led by three separate leaders: Lord Alidern Perenolde, his younger sister – Lady Beve Perenolde, and by Lord Falconcrest. Alliance and Horde are both scum to them, and each player character will be able to reach a maximum of Neutral status with them.

Syndicate Farming

Player’s character will have to kill members of the Ravenholdt Manor faction to gain Reputation Points with the Syndicate. It will be tedious as members of this Faction will give only 5 Reputation Points for a single kill. And since each player starts with 32000/36000 Hated status with this. The Faction you will have to kill over 6400 enemies to reach Neutral. It will be tedious even for Mages, that are skilled and geared up enough to clear huge packs of enemies with their Area of Effect Damage and Crowd Control.

Thorium Brotherhood

Harsh Dwarven kind living in Searing Gorge after splitting from Dark Iron clan. Some say that some members of this brotherhood possess immense talent, showing incredible skill in Blacksmithing an Armorsmithing. Their craftsmanship could be the best that Azeroth has ever seen.
Thorium Brotherhood Farming

From Neutral to Friendly, you will have to turn in various items in packs to Master Smith Burninate. At once, you will be able to contribute:

2x Incendosaur Scale, 4x Kingsblood, 1x Coal

2x Incendosaur Scale, 10x Heavy Leather, 1x Coal

2x Incendosaur Scale, 4x Iron Bar, 1x Coal

Since this Faction is mainly built on masterful craftsmanship, you will be able to gather and contribute certain items in various quests. Most quests will be repeatable and will require you to turn-in Thorium Bar, Heavy Leather, Dark Iron Residue, and Kingsblood. There will be lots of quests in Blackrock Depths and Winterspring for you to do as well to increase Reputation with Thorium Brotherhood