When you don’t have something scheduled in your calendar, work from your RTM task lists. Make sure the tasks in your Do Today list are completed today. Much of your time should be spent on Priority 1 (do this week) tasks which have no due date, but you will work on them from your context views.
Remember that you only need to assign a Due Date (hard date) if you must do the task by a specific day or bad things might happen. All of your processed tasks will have a Priority (soft date) or Someday/Maybe.