Ask HN: How to setup a small developer group

I have been working for a year as the only hardware engineer and developer in a small company. I am not a software engineer by education, but an electronics engineer: my programming skills are mostly self-learned, and I do not know much about the software development cycle. Lately we have been looking to hire an intern to collaborate on the project I am working in, and ideally to stay later with us. The project mostly deals with embedded hardware design and firmware programming, but also analyzing data collected with the hardware and a small web app for visualizing live data from the device.

Until now, I have been working out of a simple local setup (local git repos, whiteboard bug tracker, etc.). I have been searching for resources on how to setup a small developer group and best practices to coordinate with other developers. I would like to be able to provide an efficient and comfortable environment for any new colleagues. What would be the optimum structure for a small group with 2-4 collaborators?