To steal anything in most shops, get a lot of beer from the tavern. Give it to the shop owner you want to steal from. It usually takes about three or four beers to keep them drunk. Once they start swaying and blubbering, push them out of the shop. You can now steal anything desired while the shopkeeper wanders around. Be aware of your surroundings; some people might walk in if they are attracted to you. They will stay drunk for about three or four minutes, giving you plenty of time to pillage.