As I mentioned earlier, it is easy to think that you are radically changing the photograph when painting at 100%, only to find out later that the resulting imagery still looks photographic. This example compares my first painting of the windshield reflections—which still looked photographic when viewed in the context of the whole image—with my more roughed-up second try.
With the background and non-subject areas painted, it is now time to focus on the two young subjects of the painting. The grainy film-based imagery does not have a lot of detail. It will be necessary to paint in additional contrast to sharpen the faces and hands.
My primary brush for skin and faces is the Just Add Water brush (Blenders Category). This brush is the ultimate smoothing tool. It takes some practice to master, but is the best tool for the job. When starting out with this brush, you can get it to smooth colors better by reducing its opacity. However, you'll need to stroke over areas more to even the colors out. With practice, it is best to learn how to utilize this brush with opacity set to 100% for maximum speed. A good exercise to learn the subtlety of this brush is to create to adjacent areas of complementary color and practice blending the two colors together.
I spend a lot of time increasing the contrast in the faces by airbrushing highlights and shadows. I'll often add a bit of artificial fill-lighting to compensate for a lack of detail in the shadows. Altering the tonality of the background immediately adjacent to a key area like the face can help to make the face more readable. I spend as much time sharpening up the hands, as well. Hands carry a lot of expressive personality that can enhance the character of the subject.
With the image painted, I tend to get away from it for awhile so as to look at it with a fresh perspective later. In this case, I realized that my earlier rotation to straighten the now-eliminated tree trunk and weeds has resulted in the boys tilted at an unnatural angle. I used a large circular selection with a soft edge to pick up and rotate the boys back to upright, then blended any telltale distortions.
The final image with a bit of saturation added. The brush strokes are aggressive enough to still provide a painterly texture at this reduced scale. Without this aggressive brushwork, the interpreted photograph would still retain some of its photographic fidelity.
The major lesson to be learned here is that—from a photographer-oriented point of view—you need to be willing to eradicate that precious sharp photographic detail in exchange for loose, expressive brushwork. Otherwise, you'll still have a photograph.
Viva la Painter!