When you don’t have something scheduled in your calendar, work from your task lists. Make sure the tasks in Do Today list (tasks on today’s planner page) are completed today. After that, work on tasks from your context views (in the back, behind their tabs).
Remember that you only write a task on a daily planner page (hard date) if you must do the task by a specific day or bad things might happen. Tasks which only have soft dates should be written on the pages behind their context tabs, at the top of their pages, in the rough order you want to do them. A task can be written in multiple places. Someday/Maybe tasks are also written behind the context tabs, but at the bottom of their pages with “(S/M)” after the task name.