Natural history illustration is a fairly exacting discipline. I took the online course offered through EdX, one of their "Massive Open Online Courses" or MOOCs. It's free, or pay $50 for the certificate, your choice. It's a great intro to the field of scientific illustration, which has certain forms and conventions for recording and conveying observations.
Deltochilum dung beetle. I became fascinated with dung beetles (and drew a lot of them) because of Emily Graslie, who exhorts all of us to remain curious and "be the dung beetle" that makes goodness out of being knee deep in shit, which we pretty much all are at this point. Take five minutes out of your day and watch this video. Guaranteed, it's worth your time.
Trypocopris, Sulcophanaeus, and Heliocopris dung beetles.
A typical format for analyzing the form and structure of a flower, for illustration purposes. Measurements, color notes, dissection, observations.
A recent article in Scientific American discussed the forgotten benefits of drawing as an adjunct to learning. There is really no better way to learn and remember.