- No cubicles.
- Give developers a quiet environment.
- Set up a big room with plenty of space for everyone to work together.
- No fluorescent lights.
- Plenty of whiteboards and index cards.
- There should be plenty of room for developers, their managers, and some sort of customer to work together comfortably.
- Have a couple of small offices for work that needs absolute quiet or privacy, but don't give them to anyone permanently.
If you want to develop teamwork, your workspace has to encourage it. If you want people to work together — if you want developers to ask each other and the customer questions rather than guessing at the answers — it has to be easier to work together than to work separately.