Just a quick sketch up of how I currently do wings.

Basic Wing:
Just a basic wing, fingers are just curved instead of jointed, wing forearm is also just curved

Structure:
Just the basic sketch of the wing structure. General idea of wing placement.

Outer Done:
The wing forearm and the outer most finger is sketched but the inner fingers are just the sketch

Complete
The wing forearm and fingers are done. I Leave the outer finger as a simple curve while I do a single joint on the inner fingers. Webbings go from point to point and attach to the forearm just below the elbow.

The final on the bottom has 2 joints and all three fingers are jointed.