At the tutorial, you learn on how to repair your Heavy/Light Armour (Whichever you want to focus on, or both).

If you know how to duplicate stuff, then use that to duplicate repair hammers. Do not use the repair hammers yet, use them to duplicate and then get the rats to follow you and only kill the ghoul.

Loot everything and every Armour, shields, the iron helmet and all the weapons. Do not kill the rats.

As soon as you get all of them to follow you, go towards the door where you first learn how to sneak and stand there.

When your health starts to get low (or weapons) go through the door heal up, and repair and continue this until you either reach expert or master of that skill.