I will later this year start on a project (embedded hardware, C, small company) where I believe that most (if not all) code will be new.

So what experiences do you have to share as advice to starting a new code base? What have you been missing in projects that you have been working on? What has worked really well? What has not worked?

Let's limit this question to be about things that relate directly to the code (e.g "banning the use of gets()": in scope, version control: border line, build system: out of scope).