Source code control is step #1 as already stated many times. While the people you work with may not be professional developers and they won't respond to a lot of enterprise or agile mumbo jumbo. They're not low level code monkeys either and trying to treat them like that by forcing them to do things 'your way' will not fly.

You've got to survey whats out there. If they haven't used source code control then just identifying the right versions of the code (if possible) and what all the possible deliverables are is going to take a long time. Then you're going to have the task of teaching your colleagues how to use source code control and convince them that its worth their time. Start with the benefits! 

While you're doing that, find other low hanging fruit and fix those problems. 

Above all else, listen to what they have to say and work on improving their situation. Don't worry about trying to put your stamp on what they do.

Good luck!