So eventually, my 36th career I would like to do children's book illustration, (gonna have to live to be 703 to get everything done in this life that I want :P ) so notes I've run across on portfolio for that:
useful article (though it was written in 2001) by Phyllis Pollema-Cahill
portfolio should be 12-15 images. show kids of different ages and ethnicities, showing emotion and being active, animals are good too, different settings (architecture, cities, nature) and adults in proper proportion to children. Include 1 or 2 full stories (combine multiple illustrations onto a single page to get through the story quickly (like a comic)) to prove you can handle a story arc and maintain the look of characters, well known fairy and folk tales have probably been done to death don't bore the reviewer.
Direct mail helped this author the most, but the internet is much stronger now so who knows.
"A self-addressed stamped reply postcard has been very helpful to me in getting feedback. I make it as easy as possible for the art buyer by putting checkboxes in front of brief statements such as:
__ I like your illustration samples
__ Please send me a full portfolio
__ I'll keep your samples on file
__ Please send me new samples periodically
__ I'm returning your samples, they're not appropriate for our current needs.
A resume isn't really necessary in a mailing, but you can include it. A brief paragraph in your cover letter about yourself and your work might be more readable
In my experience it can take anywhere from a week to four years (seriously) to get a reply card or samples back. Most publishers seem to take about 3 months. No response doesn't necessarily mean they don't like your work or haven't kept it. "
and went and tracked down the illustration rates for Ladybug magazine (the other magazines in that series where not as direct with their rates)
# Rates: $500/spread ($250/page)
# We purchase all rights; physical art remains the property of the illustrator and may be used for artist's self-promotion.