Video Tutorial:

Brushes:

Hair sketch

First, on a new layer I start with the hairline, in this case, the bangs. For full bangs, draw lines that are open to the opposite side, and that will meet on a straight line in the middle. Working on a separate layer is better to use a tool that can move objects, this way is easier to adjust.

Define the hair length and find where the bangs are brushed down from, I like to use references, it's really good for improving. For the two buns at the top of the head, think about where the hair will be pulled from, and the hairline divided in a middle part, so its divided equally to both buns.

Let's add color!

First, on a normal layer paint the base color using the first linked brush, or any thick brush at 100% opacity so the color doesn’t overlap. You can also fill it with the lasso tool, but since I don't use line art, I like to have a better control of the shapes, and painting like this it's easier for me. To erase the harsh line from the bangs, I use both the soft eraser and the blender tool, use the soft eraser like you're drawing a bang this way it can be a bit more natural, especially when coloring the skin.

Second, with the hair texture brush (second link) on a multiply layer, use the same color from the base and add shadows to the hair. Focus on the bangs and where the hair is being tied.

Third, on a add layer, keep using the same color and the hair brush to add highlights. I like to focus in between the shadows. Then, use the hair highlight (3rd link) at a light color and low opacity, giving a doll like effect.

Summary: In this order

Add layer - Adjust opacity - Highlights

Multiply layer - Adjust opacity - Shadows

Normal layer - 100% opacity - Base color

All using the same color!!