Photoshop's maybe the easiest as you can spread it out on different subjects.
1. Photography & Photoshop - Using Filters etc to enhance photos.
2. Web - Generating web mockups and exporting files for web.
3. Print Layouts - DPI etc and saving images optimized for print output.
4. Photoshop Effects for type - Filters, Emboss, Bevel etc.
5. Editing Images - Maps etc. Simplifying a map to take off towns etc that aren't needed.
You get the idea I'm getting at. Rather than a full tutorial pick out things various people use it for and be as expansive as possible.
Hope that makes sense.
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