You could escape the flatness of monochromatic color scheme by using different textures for similar items. For example, you can mix a cotton pillow with an indian saree sequinned fabric pillow, of the same color scheme.

You could also use different finishes for every item in the room, given that you've a certain theme in your mind. For example, you can use a matte acrylic paint for the rough-surfaced wall, a glossy paint for the side table, and an exposed unfinished wood on your ceiling to achieve the industrial chic look.

Compare Etched Glass Style
Etched Blown Glass, Drinking Glass, Art Display

Compare Stained Glass Design
Choose from Hand Painted and Finely Detailed

Start experimenting the different textures available in each material, and pick the one that you love. For example, in the glass category, there's plain glass, etched glass and also stained glass.

There is no hard and fast rules in incorporating and combining textures. However, these are small pointers to note:
Rougher texture emphasize character.
Sleeky, shiny texture adds sophistication.