I knew a "pachi-pro" in Japan who explained the basics. He worked a regular job on weekdays and spent every Saturday and Sunday playing pachinko from 10am to 10pm. He said the key was to find a machine that was paying out well, and to be prepared to lose a lot until then. If you walk past a good pachinko parlor before it opens in the morning, you'll likely see a decent sized line of people waiting to get in. They're lining up to get first shot at whatever machine they think is paying out.

This guy claimed he made the equivalent of $20,000 USD per year on pachinko, on average. But that required sitting in front of the machine for 20+ hours a week, and dealing with the stress of occasionally going really deep into the hole when his luck wasn't playing out. It seemed to be more of an addiction than anything.