Colour aberration and Sharpen
I complete my scene by applying colour aberration and a Sharpen filter. For the former, I go to Filter>Lens Correction..., click the Custom tab and play with the Chromatic Aberration sliders. I then click Filter> Sharpen>Unsharp Mask, and adjust the Amount, Radius and Threshold settings. Finally, I enhance my highlights with a subtle texture placed over my painting.