Figure out some functionality that needs to exist. Within a unit test, write the top-level code for it regardless of whether the supporting methods exist or not.
...even if I haven't written populationDao.getPeople() yet.
Eclipse will complain that I have written references to methods that don't exist. Hit control-1 and choose the answer that is "create method 'getPeople' in interface 'populationDao'." Then, of course, PopulationDaoImpl will have errors, because I have a method in populationDao that I haven't implemented. Open up PopulationDaoImpl, control-1, 'add unimplemented methods,' and write the implementation for getPeople().
This way I know that getPeople() has at least some test coverage right from the start.