This is possible in PS and SAI. In sai you will need pen tool and marker/water. In photoshop two brushes. One for strands and a soft brush like below where it says 6, 19 and 19. The first three brushes displayed:
First draw a line in the direction you want your braids to be in. Curved or straight.
Next draw a thick diamond shape, boxy if possible. Then from about halfway attatch another diamond shape.
Continue this all the way down your guideline. You will end up with something like this below.
Colour a flat base. The midtone of your braid and reasons why will be mentioned as we go.
If you are a cell-shader this tutorial will give you an