It's a fairly common practice to prefix branches only intended for your own work with your initials and a slash, e.g. jd/my-work-in-progress. You can't guarantee that nobody else will work off it, but it's their own fault if they do.

We treat branches for tickets (prefixed with the ticket ID) as owned by the owner of the ticket: feel free to check out, but if the owner changes it underneath you, tough.