I start by blocking in a base color in a rough shape that the hair will take. I follow that by using the smudge tool (small pixel size - 5px or under, 95% pressure or greater) to draw out soft wisps and strands from that base - this softens the edges and gives the hair a good start to having a natural outline. From there, I use a large and soft burn brush (set to "mid tone", generally, unless I'm using a very light base color for blonde hair - in which case I paint the shadows in softly with a paintbrush in a darker blonde/light brown color), to block in where the basic shadows will lay - this gives the hair a basic shape (curls, waves, etc.) to build from. It also helps me to visualize what the finished hair will look like as I'm working (helping me to decide the angle and flow of the strands I'll be painting). The shadows need not be dark at this point - they're just enough to give a sense of movement/shape to the hair, as a starting point.
After those big basic shadows are done, I continue to use the burn tool with a smaller soft brush (20 pixels wide or so), to paint in some soft strand shapes. This gives me the basic form and flow of the hair. And, using a soft brush at that size allows for overlap of the brush strokes, giving more depth to the strands as you go. From there, I go over it once more with an even *smaller* brush (5 pixels or less) to paint in the finest strands - this can be a very long process depending on the amount of wave/curl in the hair.
Once that is done, I follow suit with the dodge tool in much the same fashion. Basically it all keeps building up from that starting point in the beginning when I blocked in those large shadows.
When I'm happy with my strands and the shape/movement of the hair, I alternate between a large soft burn tool and a large soft dodge tool to push the shadows further or bring out the highlights more where necessary throughout the hair, much in the way the light would bounce off of real hair - usually along bend in the bangs, the middle of curls - places you'd normally see highlights.
If I need to add more depth, I'll hand-paint individual strands and wisps in colors that reflect the background/surroundings. It's subtle, but it adds so much to the finished hair.
I hope this makes sense without a visual tutorial. I get kinda rambly.
Well, just from looking at your work I would say you should use stronger contrast with your hair^^ Darker shadows and brigther hightlights would do them good^^ Well... generally, when it comes to hair I always would suggest you to use a tablet, not a mouse (don't know what you are using right now).
I also would suggest you to look at these tutorials, in my opinion they're pretty good:
When it comes to drawing hair the colors also matters. Study haircolors from photographys, use the color picker if you want. Red hair for example uses to have more orange or even yellow hightlights, depending on the color of the lightsource^^ So always change not only the brightness of your colors but also the saturation and the hue^^
Yeah i have just started doing that with faces and clothes. So its really new to me. But everything looks so much better when the light and shadows are different hues. Thanks for the tuts. I don't think i found them when i looked. They should be really helpful. Thanks so much for the help