1: know your way out! Fleeing from the law is hard, specially if you need to check the way to the refugee or don't know the exact shortest route. there will be moments you will get caught, so be ready for it. Also make sure you are famillair with the patrol routes of the guards.
2: although thievery is perfectly possible in towns (outside, in homes it can be different), the amount of witnesses seeing your commiting murder will be massive and you will be seen!
3: breaking entry is the easiest crime. So don't worry bout a thing.
4: looking into a container is never a crime. So make sure you look first and then prepare to steal when you are interesting.
5: Even in the most crowded place, you can still crouch and just wait for the hidden-message to pop up to loot a container or even breaking a strongbox.
6: Even when you don't get caught, launder often. If there is one thing worse then being caught by the guards, it is being caught and needing to hand in a few 1000 gold worth of goods.