How to draw illustrations with Photoshop
Beginners' tutorial for drawing illustration from a photograph using Adobe Photoshop
I appreciate the nice illustrations in what I read. When I keep fliping pages, whether it's a magazine or a formal scientific journal, I admit that I first look for nice pictures before stopping in the article to read the text. This is mainly because English is not my first language, but I bet sexy illustrations (not only in sexual context) attract attentions. Certainly, I would like to include some of those in my articles and presentations without violating copyright law.
One way to provide a nice illustration without being Walt Disney is to do it by tracing photographs. If you are willing to learn a little more than opening image files with Adobe Photoshop, I found a very easy to understand tutorial by Darrell Heath:
Vector Tutorial