Get a list of every open task (not on backburner) that is either the first step from a project or within a category. Once activated, you'll see a new item in your sidebar called "Next Actions". When clicked, it shows the following view.

This workflow snippet uses the following strategy:

This smart lists selects items that are unscheduled tasks that aren't on the Backburner. Also, for items to end up on the "Next Actions" list they must not have the "waiting" label. 

The "Next Actions" smart list groups items by their main category.
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