This example of photomontage works well because it is visually interesting and has a lot of contrast. The photo of the woman is in black and white while the photo of the plant is shown in color this contrast makes the image stand out more.
You got: Monochromatic Neutrals You’re pretty darn cool, and your Insta theme should be too! Your feed should feature one dominant cool tone. Adjust the photo temperature and use mellow or black and white filters to create a monochromatic masterpiece!