Get to know the character(s) is important for both writting and illustrating. Here are some studies I have made.
Character study mind-map guidelines:
When forming a character, I like to think of all details that define the character, even though I am not going to use all of this information in the story itself. I found that making these studies helps me with building more believable characters and gives them an added layer of personality.
In this mind map you can see the very basic areas that are to be explored when creating new character. I usually start with these and let them trigger more detailed, deeper understanding of the character.
THE CHARACTER´S PAST - what shaped the character´s personality, what has brought him/her to the starting point of your story
APPEARANCE - it is rather enjoyable to see the character in my mind while I am writing. However, don´t be too attached to the look of your character if you are not illustrating the story yourself. It is very possible that the illustrator will have a slightly - or completely - different view of the character then you. I would also recommend to let the illustrator to have the freedom to choose the appearance of the character and not to restrine him with too many appearance hints in the manuscript.
AGE - well age is obviously very important, since the character will act differently according to its age. Therefore, some patterns of behaviour are expected in certain age, a use of vocabulary...
TIME PERIOD - is the story told in present, modern time period, or is it for example historical...
NAME - very important, for the name should sit the character well. I also think that it is wise to avoid overused nicknames and added words to the name explaining personality trait of the character, especially those that start with the same letter as the character´s name. But it might be only my view.
NEEDS and WISHES - what is it that the character aims to accomplish in the end of the story.
RELATIONSHIP WITH OTHERS
HOBBIES, WAY HE/SHE SPENDS TIME...
You can do as small or as big a character study as you feel brings value to your work. The thing here is to enjoy creating a world for your character. As long as you have fun doing it, I believe it helps in the whole process. I also like to do a bit more deeper study if I feel a bit stuck in some point of the process. It usually gives me a whole new perspective and brings me right back on truck.
And another study, not very detailed this time. However, I included some sketches of the twins here, which helps me sometimes in the studies. Also, it is a great reference to do so later, especially if you are illustrating the story. I like to list the colours I use in the story for the characters in the character study. This way, I can always go back and use the right tones, even after a long time, without having to go through trials and tests.
Usually after the word studies come visual studies in my process. I would like to show you some of my visual studies of different characters from different and same stories. The one above is a part of many more pages I have done before I settled on Gentoo penguin and its final visual look for my story Happy Hatchday. The rest is from the story The Wild Chase that features mouse, cat, bear and pair of owls.
As you see, I like to play with shapes, proportions and try variety of postures and even some emotions stright from the start of the process. Sometimes I am more settled then in other times.
For animal characters it is good to find reference images of the real animals. I sometimes even draw a few of them before I start to personalise the character for the book. It gives me more confidence after I explore the real shapes and features of the animal. It is also valuable to me to see some sort of documentary about the animal if available. It is a great source of visual references for the movements and natural appearance of the animal.
I made a lot and lot of sheets of the cat character, mainly because I was never really satisfied with the final outcome before I came with the final version of it. So, if you don´t happen to have the visual of the character quickly, don´t panic. It will come to you eventually through many tries and errors and exploration. Just keep drawing.
On the other hand, the owl character was rather easy and I did not change it much from the first sketches.