First and foremost, do not assume that everyone who ever worked on the code before is a bumbling idiot. assume the opposite. If it's code that has been running

First and foremost, do not assume that everyone who ever worked on the code before is a bumbling idiot. assume the opposite. If it's code that has been running successfully in production for years, be humble. Bugifxes, shortcuts, restraints - all are real life and prevent perfect code and documentation under pressure. The team at Salesforce.com is doing a massive re-platforming right now with their switch to Lightning. Should provide a few good stories, switching over millions of paying users, not fucking up billions in revenue.