I attended a lecture earlier on fashion illustration and the one who presented, Marcela Gutierrez, has collaborated with probably the top two most controvertial designers for the past two years: Alexander Mc Queen and John Galliano. Aside from interning for Marc Jacobs and Nylon magazine, her work also appeared in Harper's Bazaar and Dazed and Confused. Some of the mega brands that used her illustrations were Prada and Fendi.
I wish I can share to you all her illustrations because they were phenomenal! It's one thing to style and shoot a fashion editorial, it's another to actually paint a complete spread.
The key to her success was constant practice. Her first job would involve her sketching from 9am till 7pm. She also pointed out some lessons in failure - she failed in her figure drawing class but repeating it again gave her the advantage over her batchmates and look at where she is now.