Paper Doll Technique:

Hat Ladies by Lisa Tawney (Paper Doll technique demonstrated by Lisa Tawney)

Cut or punch a circle from an off-white piece of sturdy paper or cardstock. I used about 3/4 inch but any size you desire will work keeping in mind the scale of an ATC card.
Cut a small rectangle for the neck.
Use colored pencils in light tones like tan, pink, light brown, etc. to shade the face and neck to give it some color. Use a light pink to shade cheeks. 
With a very fine permanent pen, make the face. You don't have to make a detailed face - just make a small line for each eye, a small line for a mouth. Shade with pink or red colors for the mouth. Add some color to the eye area like blue or green. Maybe add some fine eyelashes with marker. Whatever you like.

To make hair, select a piece of decorative paper or cardstock in a shade you like such as yellow, brown, red, black, etc. Whatever you want. Use your head shape as a guide to making the hair. On BACK side of "hair" paper, trace the circle of you head. Use this as a guide to draw the hair. Remember to draw bangs, etc. inside the circle just as the hair would look on a face. Carefully cut with small scissors. Cut face opening where the head will be placed.

Select decorative papers for dress and hat if desired. Cut a four sided shape for the dress that is smaller on top - like a pyramid without the point. Choose your background and glue the doll to the ATC. Position everything first to decide where you want her, then glue down keeping in mind that you want her neck to be behind her dress and behind her head. You can also butt the end of the neck to the top of the dress and the other end to the top of the head. 

Shade sides of dress with pencils or ink. Shade or decorate background. 
Construct hats, headbands, etc. for your girls hair.