I can’t draw and am worried that a client will request an illustration that I cannot do. What do I do when a client ask for this?

As for a client requesting a cat smoking a cigar or even a sailboat, you can always use clip-art or contract an illustrator. I know how to draw, but my skill is not in illustration, so I hire that extra work out. Of course, I mark the cost up. Put it this way, if a client requests something give them 2 options. One would be clip-art, which is not custom and you may not be able to find exactly what they want, or you tell them you can have your illustrator come up with custom artwork. Let them know the price difference. To figure pricing on clip-art, I just roll that into the cost of my design quote; it is so inexpensive, it does not justify too much additional costs. For custom work, this could range from $100 to several thousand. Get with an illustrator and mark up the work 20%.

Here are some links for clip-art and stock photography. I suggest signing up for them when you can, or on a per need basis. Some of the sites are a pay per image program.

http://www.clipart.com
http://www.bigstockphoto.com