The theme of Milly's 2015 spring collection is "organic opulence," which I think this sketch illustrates perfectly. It appears to have been drawn primarily in pen with touches of marker. The illustration has a quick and casual feel but dramatic showing a sheer full skirt and patterned vest.
Rachel Zoe's illustration is a different style than she's shown in recent past seasons (here for example.) This sketch is simplified mod black and white with a playful element in the kicked up foot and shaggy hair, showing the 1960's inspiration even in the figure illustration.
Last but not least is a graphic statement by Lela Rose of watercolored polka dots and florals inspired by a Japanese artist, Yayoi Kusama. Again its a bit of a simplified croqui (fashion figure,) but well rendered garments and unique in that the illustration took the polka dot pattern and successfully extended it into a washed out background.
It should be noted that none of these illustrations have faces. I know a lot of aspiring illustrators struggle with facial features and these are a few great examples of successful illustrations without any. The illustrations are all cohesive and none look unbalanced or unfinished.
For more from NYFW Spring 2015, see Part 1 here.