Some clever person has come up with a fantastic technique to colour your images so that the outline is barely visible. I think it gives a kind of painted look that reminds me a lot of decorative art.
In the examples I saw, the artists all stamped their images with a very light coloured ink. I figured we could all do the same thing by printing our digital images in a very light grey tone. (There's a quick How To at the bottom of this post.)
I really enjoyed this technique and loved the end result. I found that it's important to have a lot of contrast between the different layers of the picture so that each individual element stands out, particularly if they are the same colour group, such as the petals of the poinsettia. Give it a go... start simple and use a fairly large image so you can see what you're doing. Have fun!
HOW TO: Open the image in Microsoft Word and resize it as desired. Right click the image and select Format Picture from the drop down menu that appears. On the left hand side of the next menu that appears, select Picture Colour then click Presets, which will bring up several different colours for your image. The fourth choice along is called Washout, that is what you want to select to get a very light line.