Write lots of tests first, fix the code as they break. Don't make it personal for the people who wrote it. You don't know the conditions under which they origin

Write lots of tests first, fix the code as they break. Don't make it personal for the people who wrote it. You don't know the conditions under which they originally wrote it. All else fails, join a start up early and write a whole bunch of shitty code in an existential panic.