Let's take a walkthrough of one of my digital paintings done in adobe photoshop. The brushes and exact methods used throughout were not recorded but I will make general comments on each step if applicable. The original reference for this painting was a photo taken by Epoxy5.
This tutorial assumes a comfortable level of proficiency with adobe photoshop and the brush settings, and a minimum Photoshop version of 7 or higher.
I will try to include the keyboard shortcuts whenever possible but, GraphicJunkies has a great free download for all the common photoshop keyboard shortcuts.
Adobe Photoshop is a wonderful program with great advances in its brush engine. Creating brushes is easy and intuitive. For this tutorial I use primarily one brush and below are the steps used to create it.
Open the Brushes Palette (F5)
Using your reference photo, sketch the outline and important areas of your image with a small sized brush (B). At this point I am really only concerned with the placement and rough proportions. I usually work with a few layers. I have a 'sketch layer' on top then a 'render' layer beneath, and then the background layer below that, so three layers in total. In this painting I add one more layer - a layer for the shadow, don't worry about that for now I will talk more about that in the steps coming up.
I like to block in color areas, getting a rough idea of the hues I want to use. I usually start off a bit darker and build up to the highlights. I create a layer for the coloring and painting, and call this the render layer, the render layer lives beneath the sketch layer and above the background.
I like to render all on one layer but if you are not that confident yet then you may want to have a seperate layer for your flat blocked in colors, and one for your 'painting'. I usually turn Opacity Jitter off for this step.
Block in a quick shadow - you can use a separate layer for this if you want - place it beneath the render layer and above the background layer.
Try not to use black or grey for your shadows, base the color off the colors in your painting, more advanced techniques involve using warm or cool tones in the shadows that are compliments of the temperature/color of the light source.
Adding in touches of of red and blue in these steps I spend some time fleshing things out.
In this step I start to build the highlights. I have chosen a more saturated yellow orange than the base color I had laid down. I avoid using dodge or burn settings as they can give you unpredictable or undesirable results and is often a poor substitute for using proper values and color.
Just like the previous step I continue to build the colors but this time adding in some highlights to the blue and blending in the colors. This is done by using the brush's opacity and continous sampling of surrounding colors with the eyedropper tool "I" (for quicker access to the eyedropper use the 'alt or option(Mac)' button while you using the brush tool).I wanted to really bump up the vibrancy of the image so I am playing with more saturated colors.
With a small brush I add some hairs about the body, and continue to render the wasp, giving the subject more depth. I like to zoom out (crtl/cmd + -) or use the zoom tool (Z) to add details like this and use short quick strokes with a 1 pixel brush.
More highlights and some texture to the chitin of the wasp. Again using a small round brush (like the brush in step 1).
I switched to the shadow layer and with a larger round brush I begin blending it out, softening it and making it appear more natural. Continue blending until happy.
Here is the final result, I hope you enjoyed the walkthrough!