The most important element to look for when choosing a picture is that the top of the head to the tip of the toes be visible. It must be a full body shot otherwise your just guessing what the legs or feet look like and your drawing can come out distorted if your guess is not accurate. In the beginning its also best to choose poses that are straight forward, with the head and body facing front. Three quarter poses and profiles can get tricky.
When starting your drawing keep in mind the shoulder line and the bust line are parallel to one another, as are the waist line and hip line. The high hip is also the leg that the body weight rests on and cannot be changed. Yet the other leg, the "free leg", can be positioned many ways as I've illustrated above. The arms can also be arranged in any way but a bent arm with hands on the hips always give a nice effect and adds some nice negative space to your illustration.
To begin drawing a pose from a photo it's helpful to make a copy of it (or place tracing paper over it) and draw the shoulder, bust, waist and hip lines as well as the center line and panty line, as I have done with all these images. (This helps to know where seams and other clothing details should be placed.) Then draw a loose gesture drawing to get the main muscle masses down. You can create the final sketch outline from the gesture drawing and erase the unnecessary inner lines or just layer on another piece of tracing paper or thin marker paper and outline the body. Then start designing!
To begin drawing a pose from a photo it's helpful to make a copy of it (or place tracing paper over it) and draw the shoulder, bust, waist and hip lines as well as the center line and panty line, as I have done with all these images. (This helps to know where seams and other clothing details should be placed.) Then draw a loose gesture drawing to get the main muscle masses down. You can create the final sketch outline from the gesture drawing and erase the unnecessary inner lines or just layer on another piece of tracing paper or thin marker paper and outline the body. Then start designing!
If you have any "pose" questions ask away in the comments section. This way everyone can see your question and my answer. I hope this was helpful!
All poses taken from Saks Fifth Avenue ads and www.Saks.com