Haha, I’m so glad you asked, because right now I know exactly how you feel. I’m working for a new client that, well, is a bit more responsibility that I’m used to, and definitely feeling the pressure. So, if you don’t mind, I’ll take this time to give us both a little advice.
Firstly, congrats on the project! Your first line of defense in feeling prepared enough is just that. You (we) got the project. Someone somewhere saw your work or at the very least trusted you could pull it off, and just knowing that can get you (us) over the hump of worrying about it and into actually working on it.
Something to think about is that, 15, 30, 45, any age you are as an “artist” (this includes actors, musicians, writers, etc.), there won’t be a time where you fully stop doubting the quality of your work. And there’s a lot to be said about being confident and going full-steam ahead not worrying about it, but I think the best artists DO have some doubt. I think that’s how you get better, if every time you make something, there’s something about it that makes you say “Next time, I won’t make THAT mistake”. I want every project I do to be the best thing I’ve ever done. But as far as I can tell, it’s a slow climb and you only get a little better each time.
So, there’s a little bit of comfort in knowing, whether you make something good, great, or not so good at all, in 10 years you’ll be 10 years better of an artist and hate it anyway:)
As for getting into the actual project! The best advice I’ve heard recently is from the creator of the TV show Arrested Development (Mitch Hurwitz). He says that he made something unique by knowing what his strengths and his weaknesses were. He made something BASED on his limitations. ”I couldn’t write the best jokes, but I could write the most jokes” (paraphrasing here). To give an illustration example, I’m not the best at drawing really cool action scenes. Anytime someone’s doing a lot of moving around, it’s obvious I don’t know much about anatomy and it looks weird. I stay away from it when I can. So, when I’m not confident, I stick to the things I know I’m better at. I’m alright at portraits. And I can draw someone standing still, and I can draw them standing still again somewhere else. And I can draw their clothes, and maybe a lamp. Maybe another lamp. I can pretty much draw something just sitting there, boring and still. Not a very exciting drawing, and there’s really no point or use to it. But if I put all those things together, throw in some jokes and dotted lines, all of a sudden it’s a fun paper doll, and now it’s an illustration with a point to it. There’s a million ways to draw the same thing. So, if you’re better with drawing big, sprawling landscapes, but not so good at drawing people, then fill this baby up with some beautiful landscapes. Make it from an angle that’s unique to you, something you know you can pull off, and before you realize it, you have that forever sought-after-thing called “a style”.
So, as you start on this children’s book (and I start on my project), remember you (we) were good enough to get the job; whether it’s great or not so great, you’ll (we’ll) be way better in 10 years anyway; and as long as you’re drawing the way you like to draw, you (we) will probably nail it:)