Here's a fun exercise in learning the two common identifiers of any object: shape, or silhouette, and color.
First use your watercolors to paint a nice big juicy color blob. Use warm, cool, light and dark color. While that's drying, use a separate sheet of copy paper and draw and cut out single or multiple shapes of pears, apples, vases, people, etc.
Now, move your "template" over different areas of the color blob for surprisingly luscious watercolors of pears, or apples, vases, etc.
Both these "pears" are from the same color blob above. Cut a string of "paper dolls" out of a sheet of paper and use the empty template for a fiesta of figures!
You can trace the shapes you like with a pencil, then cut them out and paste them onto a blank greeting card. If you want to use the same color blob with various silhouettes, just scan or photograph each time you change the placement and use the photos for greeting card images.