Tracking down a short

Hey all. Hope y'alls day goes great. A neighbor has an issue with their 98 Caravan SE. After it sets a few days the battery is drained. They purchased a new battery and again after a few days of not being started it drains again. They have had it tested and recharged, battery is good and charging system in van checks out good. They would like me to track down if there is a short in the system somewhere. I have never done that so I am asking you folks how can I track it down? If someone can tell me how to check each system that would be great. It is an elderly couple and can't afford to pay what it could cost to track it and repair it. So if you guys can help me save them some money that would be great. Thanks in advance.