I am presently writing a medium sized, roundel copy of the Mother of Perpetual Help Icon which is the one popularized by the Redemptorist Fathers in the 20th century.
A few notes about painting an icon from a good prototype or copy.
You can view hundreds of contemporary copies online. A full version always shows the angels of the passion, one on the left and another right, Mary and Jesus are arranged with Jesus' head looking out toward the angel Gabriel with one sandal dangling. The icon might be crowned and it might not be. The crowns were added to the icon at a later date in its history.
The colors will always be a blue mantle for Mary with a red tunic and Jesus wears a green tunic under a deep gold mantle with a reddish cincture. And so on. These colors choices suggest a Venetian influence.
One aspect of iconography, and probably the most important is how one paints the eyes. If the glance is "off" it changes the whole appearance of an icon and can even be disturbing.
Pupils not placed correctly, for example, might suggest the saint or God is cross-eyed. We want to avoid that, and instead, the goal would be for the icon eyes to follow the viewer in any direction.
The eyes of the MPH icon, when completed according to this Vatican copy, have many layers of detail and refinement, making it a comparatively advanced study.
The paint transitions in this icon are very, very subtle and blended perfectly. The faces are not as flat as one might first assume. Circulated printed copies (often several generations removed) don't show the details as accurately and these are often the ones that local iconographers use to copy.
The Vatican copy is in my possession for only a limited time. The garment details become secondary in this special situation. My goal is to complete the faces while the is icon is with me and then (sadly) finish the rest using photographic references. Updates here.