For the first part of my final story I took inspiration from both:
assignments. I took three photos (one in the bed, one in the snake, one wearing the demon head) and stitched them together.
(this tutorial will help you with that, but keep in mind keeping the camera in the exact same place between takes and not moving anything gives this the more cohesive look.)
To get the isolated colors turn on the black and white filter on Photoshop (in the center right bar) Adjust the levels if you wish.
Then while having the black and white clipping mask selected erase where you want the colors to be.
Note that I have color lighting, and the colors weren’t manipulated beyond the black and white in this photo.