If I were to setup a Drupal Development effort at a client company, I would recommend the following basic steps. Note these steps are not very in depth or technical, since those making the decisions behind them typically are not experts in development.
Setup one or more sandbox websites. It's most convenient to work on a hosted website on your own workstation, but if you have to collaborate with other team members, this won't work. Depending on the architecture and your launch strategy, you may want to use subdomains, secondary domains or just plain IP addresses (although these are at a premium until IPv6 is in full swing).
Establish a migration path or launch strategy for modules and websites that are under development. Don’t fall into the trap of depending on heuristics. Even if you bench test and try out your strategy, it’s still possible to miss some important detail and botch your launch.
Integrate your version control methods and tools. While IDE's or programming software may differ widely within a department, it's usually best if everyone uses the same tools for source control. These should work with your migration strategies and provide backups in case of data failure.