Portfolios for prospective children's book/magazine illustrators
I am wondering what is the best sort of portfolio/tearsheet/brochure to send to art directors for children's books or magazines. There is a specific magazine I would like to contact, which does not accept e-mail inquiries (just regular mail) and requests postcards, brochures, etc. instead. I know one should keep it short and sweet, but, should I be including small samples of related artwork (ie, 2-3 illustrations that depict the same story or characters), or just 2-3 examples of unrelated illustrations?