I began with a line drawing, which can be seen in my previous post. Working in Photoshop, with the line drawing visible in an alpha channel (set to 50% black), I began establishing values in gray, using a soft round brush. Sometimes working out the basic lighting without color is easier because I can just focus on considerations like form and lighting. At this stage, I don't push the contrast as much because some of that work will be done in color.
Next, I began "glazing" color over the grayscale painting, applying it on layers. I used a combination of Color layers and Overlay layers at this stage. The latter can help brighten and enrich colors.
In the next stage, still using only one or two basic brushes, I begin pushing the lighting and contrast a bit more, adjusting the color scheme and adding a few additional details. I stayed with a pretty broad approach, trying to focus on the whole without getting too immersed in details. Getting the image to read well was most important at that stage.
Finally, I added detail and texture, using a combination of basic soft and hard round brushes that come with Photoshop and a few custom brushes I've designed or picked up from other artists. Edges were softened or further defined, forms were further developed and the details were gradually added. I did most of this work on one or two layers at most, flattening the image often as I worked. I find working this way rather than building the images on dozens of layers is closer to the experience of painting with real materials and, more importantly, it forces me to be decisive.
That said, layers can certainly be used to advantage. The colored smoke from the hookah was the final touch and that was painted in a single, light tone on a separate layer. I then selected the painted smoke on that layer and applied the color on a separate, Color layer. Once I was happy with it, that too was flattened down onto the final art.
Thanks for reading. I hope this post provided a bit of useful insight.