Here's my daughter's advice; again, it may be more complicated than what you want to do. Good luck!
What I was taught to do when I wanted to re-create a photo as a drawing was to grid the photo (I print it out) and grid the paper I was going to draw on. I usually take my picture and grid it with one inch grid lines (or however many inches depending on size) and redraw the grid again on the paper. Then I just draw the lines out in the corresponding boxes and then once I'm done I erase the grid lines and I'm left with the line picture. It can get kind of complicated though depending on the size of your image and how big you want it be, if the image is smaller and you want to make it larger then how you grid the picture will be different from how you grid the paper, for example one piece I did I had to grid the picture by one inch squares and grid my paper by inch-and-a-half squares. Hope this somewhat helps!