Mark very lightly on the paper. Pencil cannot be erased well after it's painted on. Sketch areas of value and color change, not contours.

Pencil

I generally start portraits with a pale wash to let me know my values.

Let this dry completely.

Azo Yellow
Pthalo Green

Start lightly painting in features but make sure you move around the painting. Define a few medium darks, especially around hairline, clothing.

Children's portraits have very delicate brushstrokes. When in doubt, leave it a moment. Overpainting is the enemy!

Azo Yellow
Quinacridone Gold
Quinacridone Red
Pthalo Green
Pthalo Blue
Cobalt Blue

Keep moving around. I don't want to let the pattern of the rug distract from the boy's face, instead I want to use it to keep attention on the boy.

Azo Yellow
Quinacridone Gold
Quinacridone Red
Maroon Perylene
Pthalo Green
Pthalo Blue
Cobalt Blue