Create an atmospheric edit
To achieve a grey moody look, go to the HSL/Color Panel. Take the Blue, Green and Aqua Hues sliders to +100 and bring the Blue Saturation slider down to -100. Adjust the contrasting colours (here, Reds and Oranges) to make them pop out more.
Add dimension to your images in the Color Grading Panel. Raise Blue in Midtones and Aqua in Shadows, and set Blending to 50. In the Calibration Panel, add +7 to your Blue Primary Hue.
If your shot was taken in overcast conditions like my photo of the Gherkin in London, adjust the overexposed sky by using a Brush Tool to bring it back. (Brush settings: Exposure -1.86, Contrast +53, Highlights -26, Shadows -62, Whites -36.) Use a Radial Filter to dodge (lighten) the subject. (Exposure +0.51, Contrast +7, Texture +6, Clarity +12). Burn (darken) the areas around it. (Exposure -0.79). This is a simple way to bring the viewer’s attention to your main subject rather than getting distracted by the flat brightness of the sky area.