Here is a passage I thought might be helpful for you when it comes to deciding what to illustrate out of your text (that I will post next for you). This is written by Quentin Blake and is found in page 57 of his excellent book 'Words and Pictures'.
" Work on a book (one for which I haven't written my own words, that is) begins when the typescript arrives from the publisher; and it begins with reading. In a sense I'm reading the story as if I were two people at the same time: a normal reader, who is relishing a good story for it's own sake; and an illustrator, who is on the look-out for good subjects to draw, good moments. I probably read the story several times to get to know it, and I make underlinings and notes in the margin so that I can easily find the bits I want to refer back to later. Most of my choices I make by what feels like instinct; but when I look back on them I can see that what the illustrations are doing is not always quite the same thing on each occasion. [sic]"