Three Very Important Rules...

...for working with things you know nothing about

First Rule: If you don't know what it does, don't change it.
Second Rule: If you don't know why something works, don't assume you can make it better.
Third Rule: Only change one thing you don't know anything about at a time. In fact only change one thing at a time even if you think you know what each change will do.


Note: I've mostly learned these by making changes on the behalf of others only to end up having to go back and analyze the thing and actually fix it.