This one I decided to start with is Illustrating Children's Books: Creating Pictures for Publication by illustrator and teacher Martin Salisbury. Please, keep in mind the version I got is the Spanish one (with the same cover of the image above), the English version may have a different cover, one in blue, but with the same title.
I really like this book, it's all full color with really nice illustrations from different artists. Martin Salisbury's tips and instructions can be really useful if you have the right attitude to learn from them. Keep in mind, it's not a "how to" book. It gives you general information about how you can prepare your work for it to have quality and in the best of cases, to be published. It's not a step by step book.
If you are interested about the process of creating a children's book from the start to the end, it's a good book for you. I think it's the best choice if you are a beginner in illustration, as many of the things in this book remind me of my Illustration studies. This one has some interesting chapters, such as illustration's history, different techniques and materials, character development, about non fictional illustration, and more.
It's not a "heavy" book, it's light, fast and easy to read, but some people may find it's information too superficially, that's why I told you I think it's better for people who is starting, though you can also learn something new, it depends on you ;)
That's all for today!. Tomorrow I will show you a new illustration. Let me know if you would like to read about some of the books I own.