Thank you, Chris, Alastair, and Jean-Noël for your feedback.

I do want to set some additional context here:

• I am familiar with and comfortable with Git, although it is new to the technical writers on this project. (And perhaps frightening to the manager.) I started using Git when the DITA-OT project moved to it from SVN, and I'm still grateful for all the help that Jarno Elovirta, Robert Anderson, and Roger Sheen gave me as I learned Git.
  
• Yes, good practices for Git are just standard, good software development practices: Keep feature branches discrete; update feature branches by pulling from the current development repository frequently; commit thoughtfully and frequently with good commit messages, so that cherry picking is a possibility.
• For this project, the technical writers are using oXygen, and we can control formatting through common project files to reduce conflicts.

That said, version control with Git can have a steep ramp-up for technical writers. Any thoughts about how to best minimize that? Useful resources?

And how to best plan a process for the scenario in which a writer wants to merge some (but not all content) from a feature branch into the development branch? In the absence of granular commits with descriptive commit messages, cherry picking is a not a realistic option.

So far I've handled this manually, by asking the writer for names of the files that she wanted merged; merging them into a local copy of the development branch; resolving merge conflicts and QA errors (errors in DITA source, spelling); and eventually merging into the development branch.