Well, wings and skirts are the hardest things to rig properly. Wings have to be designed with the spines at certain angles =in order to rig them to fold properly. EtuJedi's bird wings ended up with over 50 groups to make then actually work properly.

Only advice other then the book I mentioned, was to look at the base mesh of a figure you have with similar wings, and see how they are rigged.

(I used the Daz wyvern 2.0 as my base idea.)

Way too many people take way too many things way too seriously.