This is an assignment I use in my Plant Diversity and Evolution class the week before they start their iNaturalist project. The students learn how to take great photos and how to take horrible photos of plants, how to crop photos and how to generally think about photography for plant identification. This is not how to take artsy photos or the most gorgeous photos ever, this is strictly utilitarian and pragmatic.
Presentation slides (pdf): Lecture: Plant photography for online identification (240 downloads)
Worksheet for students: Worksheet: How to take good and bad photos for online plant identification (161 downloads)