That’s a great question, @Sarah_Kirkpatrick and there’s a few different options for this.
The first solution is to have them create the tasks from their My Tasks list within your workspace. Tasks created directly in My Tasks start out as private by default, and it’s a great place to manage private, personal to-dos. This is a good option if their tasks are related to your organization but are personal to them. You can see more about My Tasks here: https://asana.com/guide/help/fundamentals/my-tasks
The next option would be for them to create private projects for their own tasks. This would be a good option if they have dozens of personal tasks related to your team’s work. You can see more about private projects here: https://asana.com/guide/help/permissions/project-permissions#gl-private-project
The other option would be for your contract writers to set up their own workspaces to manage their tasks. This would be a good option if the to-do list they want to manage is completely separate from your work. You can see more information about workspaces here: https://asana.com/guide/help/workspaces
Do you think any of these options will work for your writers?