Choose a favorite author and read many picture books by the same author. You can compare photos, language, rhythm, theme, etc in the books
Mopar I know teachers do author studies but I have seen some complex set ups. Things I would not want to take on. I love the idea of just reading the books and comparing photos and themes. I love the idea.
I have done Author studies on Jan Brett, Dr. Seuss and Eric Carle. I do the same as mopar with comparing pictures, language, etc. We also learn about the author. I then do some kind of activity or art project to go along with the author study.
Learning about the author is great! If you can visit the author's webpage that might be fun. Maybe writing a class letter to the author (some of them actually respond).