One of the first things I would like to point out here, are the two books I'm reading right now,
one is called "Starting your career as a freelance illustrator or graphic designer" written by Michel Fleishman, in English and the second one is called "Professiya illustrator: uchimsya myslit tvorcheski" which is obviously in Russian. English title is "Profession - Illustrator. Creative thinking" written by Natalie Ratkovski, a russian illustrator, living in Germany and I've been following for a while now.
Both books seems to be very interesting and I'm planing to post more on them,
as I will come along with reading.
Book "Profession - Illustrator. Creative thinking" Publisher "Mann, Ivanov & Ferber", Moscow 2011
(In Russian: "Профессия - иллюстратор. Учимся мыслить творчески")