Jagex introduced items called blackjacks during Feud, The quest. These are very handy in pick pocketing, because depending on the type of blackjack, it can stun your opponent for a certain period, allowing you to pickpocket them successfully without being stunned. Although you can only use them on the NPCs in the quest city of Pollnivneach, blackjacks are a great way to train until level 71 because it is the fastest training method allowing you to get 150k experience an hour. However, it also requires concentration and many clicks, placing it behind Pyramid Plunder in this manner.
Another way to gain experience quickly, especially at lower levels such as 45–71, is to do the Sorceress’s Garden. The gardens are four seasonal mazes in which lie corresponding elementals (Summer, Autumn, Winter, and Spring). The object of each maze is to either reach one of the two ends: The herb patches (which are easier to reach), or the Sk’irk fruit trees at the furthest point of the maze. When you take herbs or a fruit, you are automatically teleported outside by the main fountain. There are many ways to make your way through the gardens but players usually find small quirks to shave time off of each run. This can be and is a very effective way to train thieving if spam clicking or Pyramids aren’t your thing. See our Sorceress’s Garden guide for more information about them.
Osman from the Sorceress’s Garden minigame gives very generous thieving experience in exchange for Sq’irk juice. However, it’s probably better to make money rather than try and get all of the Sq’irks required for the juice.
Although not much information has been gathered depicting experience, after doing the quest Buyers and Cellars, you will be granted brief access to the Thieves’ Guild. Blackjacking here may be a good idea if you need a change of scenery; the experience is rather close to Pyramid Plunder.