Step 01: Creative curves
Add a Curves layer and create a S-shaped curve to increase saturation and contrast. Add another S-shaped curve with the red and green channel and an inverted S-shape for the blue.
Step 02: Add a Blending mode
Add a new layer, paint it black and set the Blend Mode to Hue. Decrease the Opacity to 30%. This will add a subdued look without dampening the original colours too much.
Step 03: Use unsharp Mask
Change the Image Mode from RGB to Lab Colour. In Channels select Lightness. Add an Unsharp Mask filter, set the Amount to 80% and the Radius to about 50. Change the mode back to RGB.
Step 04: Place Dark Edges
Create a new layer and use the Paint Bucket to colour it black. Set the Opacity to 50% and use a large soft eraser to remove the centre and leave the darkened edges.