When you don’t have something scheduled in your calendar, work from your Astrid task lists. Make sure your tasks in your Do Today list are completed first. Afterwards,your time should be spent on priority tasks which have no due date, but you will work on them from your major context views.
Remember that you will only assign a Due Date (hard date) if you must do the task by a specific day or bad things might happen, or when you decide a task is going to be done today. All your processed tasks will have a priority (soft date) or Someday/Maybe (included in the SM List).