Until you become skillful at painting action figures, you can stick with using flesh tone for the face and other exposed body parts. The paint is available at art supply stores and comes in various sizes of tubes. A small tube will last you a long time. Let the paint dry. If the figure is dressed in battle fatigues, use a drab olive green.
Boots can either be black or light and dark green.
If you are unsure of the color scheme, look at a soldier s garb in a magazine or book. Now go back and provide the details. When you are satisfied with the look of the basic figure, you can let it dry and then add a protective coat of Dullcoat. Position the figure in or next to your model. If you want it to be a permanent part of your model, cement or glue it in place.