This is pretty straightforward guide. For levels 1-90, you are pickpocketing the highest Thieving levelled NPC that you can pickpocket which are shown below. There are various exceptions to this due to some NPC's not being found where they should be located or the NPC's pickpocket option not being functional. Once you reach level 91+, you have two options: Dwarven traders in Keldagrim or Elven Workers in Prifddinas with each having its own pros and cons (see below). I will update this guide once more thieving NPC's are added and also functional.
Note: It is generally assumed that you know how to go to the various locations or know where certain NPC's are located in the maps provided below. I have provided information on how to get to certain locations that some may people may not know about but if you have questions about the guide, feel free to ask them below and I will try to respond as quickly as possible.
Levels 1-10: Men (Lumbridge)
Levels 10-25: Farmers (Northeast of Lumbridge)
Levels 25-38: Warriors (Varrock Palace)
Levels 38-45: Master Farmers (Draynor Market)
Levels 45-55: Fremennik Citizens (Rellekka)
For this training method, you will be pickpocketing the various citizens found throughout Rellekka. It is recommended that you pickpocket the citizens found in houses as they will have a smaller area to move around in and also avoid pickpocketing the NPC's near the market as the guards near the market will turn aggressive if they catch you pickpocketing. The easiest way to get to Rellekka is through the lodestone system by selecting the Relleka lodestone and then running west. Skillers should also be aware that there are aggressive unicorns near the lodestone.
Levels 55-70: Knights (Ardougne Market)
Levels 70-75: Paladins (Ardougne Market)
Levels 75-80: Gnomes (Tree Gnome Stronghold)
To get here, talk to Lady Deathknell at home and select these options: Skill Training < Agility Courses < Gnome Agility Course. Gnomes are located throughout the Stronghold and you have various options for banking if your inventory becomes full. You can either use the bank located in the Tree Gnome Stronghold, use the Spirit tree to teleport to the Grand Exchange and back, or teleport home and then talk to Lady Deathknell to teleport back.
Levels 80-85: Heroes (Ardougne Market)
Levels 85-90: Elves (Lletya)
For this training method, you will be pickpocketing the various citizens located in Lletya. To get to Lletya, you can teleport to the Tirannwn lodestone and follow the path in the image below. You can ignore the leaf trap since you can walk around it and you can also ignore the trip wire since you can walk directly over/past it and not be hurt by it. A bank is also located in Lletya if your inventory becomes full.
*Ignore that Tirannwn is misspelled, I did not make this map.
Levels 90+: Dwarven Traders (Keldagrim Palace)
Pros: Best thieving XP/Hour, Supplies for Smithing (god tier for Ironmen), Caveman Only Ironman Friendly, Keldagrim has no requirements to be accessed
Cons: Guards are annoying if not trapped, Not afk, Keldagrim not Master race
The easiest way to get to Dwarven Traders is to talk to Lady Deathknell located at Home/Combat Academy in Lumbridge and select these options: Skill Training < Mining < Lava flow Mine
After you select these options, you will be teleported just outside the Lava flow Mine (Beside the Blast Furnace building). Run west to the Palace and go to the second floor. In the center of the second floor, you will find the Dwarven traders as well as Guards which can be a nuisance if not trapped properly.
Levels 91+: Elven Clan Workers (Prifddinas)
Pros: Semi-afk, Some useful items, Master race Prifddinas
Cons: Locked behind 1500 total level requirement for Prifddinas, Need 93+ Thieving level to be worth training here without waiting for clan cooldowns, Some junk items, Second best thieving XP/Hour
Before you can pickpocket Elven clan workers, you will need access to Prifddinas which at the time of writing this guide requires a total level of at least 1500. To get to Prifddinas for the first time, you will have to either use a fairy ring to teleport to the fairy ring located in the Amlodd clan district (code DJS), use any Spirit tree to teleport to the Spirit tree located in the Cryws clan district, or use the south entrance which can be accessed from going through the forest in Tirannwn/Isafdar. After getting into Prifddinas, you can activate the lodestone in the center of the city to unlock a quicker way to access the city permanently via the lodestone teleport system.
Prifddinas has eight different clan districts and each district is aligned to two different skills each. Each district has elven clan workers which can be pickpocketed for various items relating to the two skills of their clan. Elven clan workers also have various Thieving level requirements depending on their respective clan (see table below).
It is also worth mentioning that unlike other NPC's that can be pickpocketed, you will automatically pickpocket elven clan workers until you stop or until you are caught. If you are caught, you are given a strike and if you get three strikes, you will be unable to pickpocket elven workers in that particular clan district for 20 minutes. Due to this, it is highly recommended that you have at least level 93 Thieving before pickpocketing elven clan workers in Prifddinas since multiple clans will be on the 20 minute cooldown and you will rotating between various clan districts.
Generally, you will be pickpocketing the elven workers in the four best clans you can pickpocket in and switching between these four different clans. It is also worth looking at which clans the Voice of Seren (VoS) is active in as Thieving XP is increased in clans in which the VoS is active in for its duration.
*XP amounts listed are the XP amounts before the server XP multiplier is applied.