Whether you like it or not, stealing in Kingdom Come: Deliverance is an essential skill to become proficient in if you want to complete specific quests. While for the most part the techniques of stealing are relatively simple to grasp, there are a few things to keep in mind for each method:
Pickpocketing is a risky business. The first thing to do is receive the initial training provided by Miller Peshek at Rattay Mill. Once you know the basics you can go out in the world to practice the skill. The best ways to increase your chances of success involve considering your attire and the setting of the act. In terms of attire, wear as little as possible and remove any items with high noise ratings. Never run, and keep in mind that crouching near the target will reduce the level of noise you make. In terms of setting, it is recommended to pickpocket only when you are sure that there is no one in the vicinity who might catch you doing it. When possible, choose to pickpocket at night to find cover in darkness. Another advantage of pickpocketing at night is that you can sneak into the sleeping quarters of the target and pickpocket them as they sleep, thereby minimising the risk of being caught.
Note: When pickpocketing at any time take care not to bump into your target or get too close to them, even as they sleep. If they detect your presence as you initiate the process of pickpocketing, they will alert the population to your status as a thief and your reputation in the associated region will be reduced.
Lockpicking is perhaps the most common way in which you might find yourself stealing. As with pickpocketing, the setting and time of day will influence your chances of success. If you are attempting to steal from a chest or house with guards patrolling nearby or residents in attendance, take the time to note their movements to determine the most opportune moment of action. The chests and doors that you are capable of successfully opening is based on your lockpicking skill level and the difficulty of the lock. Lock difficulties range from very easy, easy, hard and very hard. There is also a range of difficulty within each category; where you open one hard chest, another might be impossible to open until you gain sufficient experience. It is a good idea to spend some time (preferably at night) picking locks that are within your range of capability to gradually increase your lockpicking skill level. As you level you will unlock specific perks that will make the whole process much easier.
Knock out / Stealth kill
In order to ensure that you acquire the items that you aim to steal without being caught, you can take the more drastic measure of knocking out or even stealth killing the target before you steal from them. This can be done by crouching behind or over the target while they sleep and choosing the desired option as seen below. While this method ensures success in stealing, there is also a good chance that your reputation will be reduced in the associated region and the risk of being interrogated by guards significantly increases. If a guard finds any stolen items on you, you will be sent to jail and your reputation will take a substantial hit. You can however use persuasion options to encourage the guard to turn a blind eye.
Selling Stolen Items
Any items that you steal by pickpocketing, lockpicking or hunting in the case of poaching cannot be sold to most vendors. You can identify stolen goods in your inventory by the presence of a red hand icon. Inspecting the item information will also tell you where it was stolen from. The easiest way to render a stolen item yours is by travelling far away from the place where it was stolen and waiting a couple of days. The people in different regions will not recognise the item as stolen since it is unknown to them, the residents of the place where it was stolen will soon forget. Once stolen icon has disappeared, you can sell the item to any vendor in any region except the one from where it was stolen. If you cannot afford to leave a region you can store the stolen item in your horse's inventory or in a home chest and wait for time to pass without the risk of being caught by guards. Finally, if you want to immediately sell a stolen item you can visit Miller Peshek in Rattay Mill or his associates Woyzeck (located at Kohelnitz, the mill by the river North of Rattay) and Simon (located at Sasau Mill).
Note: There is a small chance that you can sell stolen items to regular vendors which can be increased with the level twelve Speech perk 'Trustworthy Middleman', but it is not recommended to attempt to sell any items of high value as this may result in an arrest.