If you have Photoshop or Photoshop Elements on your computer you can turn your photos into interesting illustrations using the stamp filter. The stamp tool is located in the filter menu under sketch. Its function is to posterize your image into the two colors you have chosen in the color picker (located on the tool bar).
Start with a photo that has strong contrasts, either between the subject and background or within the subject itself. Choosing contrasting colors in the color picker will also give great results. Choose two colors that you enjoy together and then give one color a little twist by picking something slightly bolder or greyer than you normally choose. For example, red or blue might twist towards tangerine and violet or mauve and periwinkle.
Here I used a photo of our cat, Tigger, who hopped into my photo booth recently (she's usually camera shy). In the color picker I chose a dark teal foreground color and bright yellow background color and then applied the Filter/Sketch/Stamp tool. I played with the sliders within the stamp tool's menu box until I got the level of detail I wanted and then clicked "OK". Voila! Instant art you can print and use as you wish.
Here are some examples of photos of flowers taken in my garden. Use the sliders in the stamp menu to fade out background details you don't want to see. In these photos the tangle of leaves became the larger masses of color while the flowers/berries pop forward.
In this image I added a third color (yellow green) around the vase of flowers. After applying the stamp tool to my photo I re-colored the space around the flowers by selecting it with the "magic wand" tool and filling it in with a darker color picked from the same palette as the vase.
I like how modern and summery these images turned out. Other subjects such as autumn leaves, pumpkins or a door wreath would make charming fall cards and decorations. Try it and find out for yourself how easy this is!