To get this design I took a photo of my son and using Paint Shop Pro ( a graphics programme) I took out the background, reduced the number of colours to 16 and put the contrast up a bit.
When painting I didn't try and stick to the "real" colours in the picture, instead I used my own interpretation. When I do this style of painting again I will ensure that out of the colours has sufficient contrast between them. In this example the black and the dark brown I used were too close to give a decent level of definition
The main thing to remember when painting without outliner is: the longer you leave the paint to dry before you paint an ajacent area the more defined that area will be. The quicker you paint an adjacent area the more it will blend.
The video at the bottom of the page shows the portrait being painted, speeded up 8x. Its not the most interesting video in the world and there is no commentary.
If you do this type of project a go we would be very interested to here how you got on with it. Maybe you'd like to post the results in the gallery and use the forum to let us know how you got on with it.