One of my favorite ways to make quick yet eye-catching cards is to stamp on kraft notecards and add color with pencils.  

If you apply the color heavily, it really looks great.  And then, by adding highlights with a white pencil, the images pop.  You can make many great cards very quickly with just about any style of stamps.

You can also stamp with White Memories Ink on kraft for a great look.  And, even better, you can color right over the white stamping for soft colors.

This technique works with any stamps - gotta love that!