1. GET THE UNDERTONES RIGHT
This is so key to a successful monochrome scheme. If you are going to layer different shades of the same hue, you really need to make sure that they have the same undertones. As Tash and Tom both mentioned, pick one main color, then layer with shades of the same hue but different tones and tints (darker and paler versions of that core color).
2. TEXTURE IS AS IMPORTANT AS COLOR
A monochrome scheme needs plenty of texture. Using a single color does risk looking a bit flat, so the texture will add to the depth and interest. This is especially important if you are decorating with neutrals so really need some contrast of materials going to ensure the room doesn't look dull.
3. CONSIDER HOW YOU WANT THE ROOM TO MAKE YOU FEEL
We all are aware of the impact that color can have on your mood. So when you are taking one color across the whole of your space, you really need to consider how that color will make you feel. How do you want the room to feel?
4. ADD INTEREST WITH SHAPES AND STYLES
'When you strip back to just one color, you need to be very considerate with what furniture and decor you bring in, they are going to be doing a lot of the work to ground the room and prevent things from looking too flat,' suggests Jennifer Ebert. 'Look out for interesting shapes and silhouettes. Blend styles, mix old and new, and pieces from different eras to ensure there's plenty of character to the room.'
5. BREAK THE RULES WITH CAUTION
Adding an accent color to a monochrome scheme is something that should be done with caution as it can look forced and you can lose that tonal look that a monochrome scheme is all about. It can be done, you just have to do it carefully.