Copying art isn't always plagiarism. If you take the idea and make it your own then it's not plagiarism. Even if you take some of a piece of art and add to it then you're not copying because you made it your own.
The warm up I learned the most from was when we tried the different mediums and blended them together. I learned the most from this because I figured out how to make new colors and how to make it flow instead of it being blotchy. I also gained a new perspective instead of using just black and white all the time it might be good to add color but be comfortable with it as well.
I think illustration Friday's have helped my skill levels a lot,some more than others. One of the first ones I did helped with my realistic drawings and also shading. Some others have helped with creativity, brainstorming, and also adding some color. There's not a set thing to do just a theme to go by and you don't want to do a mainstream drawing that everybody else is doing so you have to think creatively to make it your own. Also I used to do a lot of black and white but with most of the illustration Friday's I went out of my comfort zone and tried to add color to it. So it helped more than I thought it would