Use Scrum!
The Scrum methodology works quite naturally with Drupal development, if you use it right. Every group modifies it; I've yet to see a single company that actually uses Scrum as it's defined in the Scrum Guide, though some come close. However, it's such an inspiring and well-written document (and so short!) that everybody should read it upon joining the team:
-end developer, a writer, deployment/dev ops, and maybe others. There can be a dedicated scrum master, or the site builder (not one of the coders!) can fill that role.
- The Scrum guide suggests one month sprints, but that's far too long for web development. Either two weeks (the most common) or even one week sprints.
- Almost everybody does the daily scrum wrong. It's not a daily status report. It's not for the project manager. It's a chance for the dev team to sync up with each other. The scrum master and product owner don't even have to be there. But the rest of the team should listen attentively and be involved. At the end of the daily scrum, every team member should be able to say what every other team member did yesterday and what they're planning to do today -- because they should be ready to help them, if they can.
- One more thing about the daily scrum: The three "daily questions" that are traditionally answered are "what did you do yesterday, what are you doing today, and is anything blocking you." The first two are pretty straightforward, but pretty much everybody screws up the last one! Programmers have a lot of pride, and they think they can solve any problem, so they'll always say "no blockers". That's not actually helpful. Instead, each person should say what challenges they're facing, and give enough detail so that if any other team member knows something that can help, they can volunteer it.
Done right, the daily scrum should be over in 5 minutes; it's so fast that nobody should mind. And you must do it every day; otherwise it doesn't work.