Pick your targets well. Always know how to get in and get out again. The guards are never your friends, and they are always watching.
A thief has the ability to steal items from other players, some monsters, as well as various chests located throughout the world. By targeting specific items a thief can render another player useless.
The ability to steal from other players is highly regulated and a thief must first become a member of the thieves guild before they are allowed to steal items from innocent players.
Stealing is an activated ability that you use and then target either an item in another players backpack, or in a shopkeepers strong box.
Stealing is trained through repetitive usage of the skill. As with most skills, the harder something is to steal (in this case by weight of the item) the better chance you have to gain skill. For the best chance to gain skill try to steal an item that is equal to your stealing skill divided by ten and rounded down in stones. Therefor at a skill of 67.0 a player would have the best chance to gain stealing an item with the weight of 6 stones. Likewise at 89.8 skill the player would have the best bet with an item weighing 8 stones.
As a new training thief is unable to steal items from innocents the best way to train is by stealing items from friendly guildmates (who don’t mind you training on them) or purchase a pack animal and place items you wish to steal in their pack.