This was the material that I worked on during my mentorship with Joshua Lynch (https://www.artstation.com/joshlynch). My main learning goals were getting a better grasp on the basecolour, and detail distribution. I spent most time honing those particular skills, but also had fun learning new tricks/nodes I haven't used before. I'll be applying what I learned to older works as well, and to new works coming to my Artstation marketplace store.
The tutorial on presenting and rendering materials by Josh was also super useful. I expect many material renders to start all looking very similar, but don't consider that a bad thing, since it levels the playing field and will show skill even better perhaps.
I can highly recommend even experienced artists to look into the Mentorshop coalition, since it's a great way to grow as an artist.