This is a typical illustrator/editorial collaboration for an educational illustration project, even though we were continents apart…
The brief comes in; mostly written with a few examples of what has been done already. In this case it was for one illustration for an educational publication.You sketch and send back the first draft of ideas. They are almost always sent back with notes, like a positional guide. You make another round of sketches, this time following the brief more tightly and accurately. For me the second or third round of sketches is the last one and I make the sketches more finished In this case I pointed out where I had placed the required features. If there is time (often there isn’t) I’ll add some colour or my signature black line in the hope of giving some extra assurance that I have got it right (finally). A couple of days later you get the go-ahead to do the colour art (I prefer to sketch and sketch but to paint less). I will have already decided how I would tackle the colour, or been asked to work in a certain way.
The Illustrationist 