heres a mini tut for you, it assumes you have basic photoshop knowledge.
1) Create a new layer, name it "Guide"
2) set it to about 3 point, and black.
3) draw a basic stick figure in the post you want.
4) select a large round brush, and place the head. Select a smaller brush and place the chest joints.
4) Now, this part is just judgment; you will want to fill in the rest of the joints depending on how far away from the viewer they are ( ie perspective). So place the closest one, make the brush slightly smaller, place the next one, etc etc. Until all the joints are filled in.
5) Now select the line tool, make it nice and fat, and draw the rest of the body parts in.
6) New layer! called 'Joints'.
7) Fill in all the joints as previously, but use the colour that you want the joints to be.
Shade each joint by hand or using the gradient tool
9) Make another layer called "Body" and fill in all the biceps, triceps, legs chest etc.
10) shade them by hand or by gradient tool.
11) Go back to your Joints layer and use the freeform cut tool to remove any parts of the joints that would be hidden by the body
12) place the joints layer ontop of the body layer.
13) paint on any texture details, such as head texture and body textures.
14) Your done, add any back ground and other toris.
... enjoy, its pretty simple really.