You, the illustrator, have been chosen to illustrate a manuscript. Your publisher thinks it fits your style. It is a story about a magical jumping frog with some big problems. You might have some as well. Truthfully, you have never had much contact with frogs.
For any picture book there will be an amazing amount of time spent drawing, painting, collaborating with an editor or art director. There will also be a certain amount of research to be done. Even a book about an imaginary frog will take time on the part of the artist to not only interpret the vision of the author, but to actually take a look at real frogs.
Did you know you can stop a video on You TUBE while you make a quick sketch of your subject? This can be very helpful if you don't have much access to the real thing.
You may want to watch the way a real frog moves. What does it look like in and out of the water. How does it jump. How does it catch food.
The searching and gathering of the information is step one. The next step is to fit the character you are drawing or painting into the specific style of the manuscript and your own artistic style.
You may need to provide extremely detailed and realistic illustrations. On the other hand you may need to be quite whimsical in the approach to the character. This is true not only for frogs as noted in this example, but for all the characters. Humans, animals, and anthropomorphic animals need to have one thing in common in a picture book: "Character."
The above illustration was used for T shirt design
Even Lizards can be comical or whimsical and still be based upon the actual observation, photos or videos of lizards.
How do you arrive at the essence of your character? Partly through the manuscript. Partly through your own talent and experience and partly with the aid of the editor or art director's comments.
Finding the right tone for an illustration will depend upon the tone of the text. An illustrator will do the best job for a client when the illustrator has a good grasp of the manuscript and has read it over a number of times. The effect can be different with each reading. Some facts that jump out at first may become less important if another aspect of the story seems to be more important for the reader to "see." This can also mean not using an illustration and substituting it with another. An illustrator needs to be willing to give up some images just as a writer needs to be willing to give up extra words.
My best advice to any illustrator is to always have a camera with you as well as a sketchbook. If you are lucky enough to see something unusual, interesting, or something that actually pertains to the work you are doing at the time, you will have the tools you need to record the moment. You never know when an opportunity for a great resource will pop up right in front of you.