[EricH]

Originally Posted by StevenB

Teach them version control. It doesn't matter what tool you use, but getting into the habit of documenting your work is essential.

...

If you're fortunate enough to actually have several people working on the software, keeping track of what you've done and what has changed is essential, even if all of your code is in one place. You don't ever want to be stuck in a situation where "Johnny changed the code, and I don't know what he did, but now it doesn't work...".

And version control programs can also keep a copy of the last version of the code known to work handy, for when the above situation happens 5 minutes before a match. Not that that will ever happen...