Fashion Frog – free fashion flats and croquis

Fashion Templates – tips for drawing children’s fashion

Fashion Design: from sketch to boutique – from co-owner of Baby Fabulous

Threads Magazine – the croquis family: includes six figures: average woman, petite woman, plus-size woman, average man, child, and toddler.
… or just search google images for  “free croquis” and “fashion flat sketches” and you will get a bunch of images you can use for your fashion sketches