Below are some examples of student collage portraits. They can be realistic or stylized but the elements need to guide the veiwer's eye to the face. They should be connected ideas. You can unite things via color such as in Uma's and Jesse's portraits or use guiding rays or lines like in Jesse's and Liam's portraits. More Notable Collage Artists examples are first.
Notice that Uma painted different strips of color for her hair and then cut them out and pasted them with cartoon elements that she drew and painted around the face that she painted. She also cut magazines up for elements of color. You can use anything you think is interesting such as buttons, yarn, other found objects like concert tickets, stamps, etc.
Liam used painted parts like the cogs, the background and part of the face. He also used yarn, photos and cut magazine elements. Liam's clearly tells a story about how we are controlled by technology or social media.
Jesse created a very stylized portrait from looking at the work of artist Henri Matisse. Notice how she used guiding lines, (rays,) that point the collage elements to the face. I like the funny googly eyes, buttons, flowers and drawn flowers as well as the watercolor and pen and ink elements. Everything goes together because of color and the rays. It is unfortunate that I did not photograph it better.