Comment Documentation and comments. (Score 1) 344
I wish I had a dollar for every time an OSS project spat out something like "ERROR: 0947445" with no mention anywhere of what aforementioned error code meant or how to fix it, then upon further dredging through a hundred uncommented lines of code to find out what was going on it turns out that the root cause was that I hadn't installed some-package-to-do-something-2.4-beta (which should have been a prerequisite, but isn't).