For this tutorial, choose designs that are solid black and that don't have very large solid black areas. You also want a fair amount of detail but nothing too thin or fussy. You will get an idea of the kinds of designs that work the best from the examples below.
Download the tutorial HERE.
Included in the ZIP file are all of these example images and the line art images that I used to create them. The line art examples posted here have been reduced in size but the ones in the ZIP file are full size.