As a geek and an amateur illustrator of dinosaurs, among the mostr frustrating and most difficult thing to draw in the right way are the wings of Aviremigians (i.e. the clade that includes Yixianosaurus, Oviraptorosaurs and Paraves). Expecially when they're folded. Rarely you can see good reconstructions in this regard. The most common errors are the orientation of the feathers (generally in a very chaotic way) and that of the wrist. The latter in particular is the most relevant. The wings of most species more primitive than Aves are different, although at first strikingly similar. How to get them right then? On my blog, I give some useful tips to know how to restore them properly, but in an amatorial way.
1. Bare naked.
2. Arm feathers.
3. Hand feathers.
4. Final result
I hope this will be helpful to you all.
Read the full post here: [link]
EDIT: corrected some terminology and added thoughts on scapulars.
References: Scott Hartman, The asymmetry of the carpal joint and the evolution of wing folding in maniraptoran theropod dinosaurs, Animals Real and Imagined by Terryl Whitlatch
Ps: Sorry for the colours' quality. Bad scanner