one simple rule: we'll add a new automated test every time we fix a bug. Following that rule will start to immediately get testing where it's needed most: in the parts of your code that have the most bugs and, therefore, drive the most waste for your developers. Even better, these tests will start to pay immediate dividends by propping up that most-unstable code and freeing up a lot of time that used to be devoted to finding and fixing regressions (aka "firefighting").