Dear twocolor:
After reading the comments here, I felt I should add some comments to cover the important and frequently overlooked topic of lighting. If ones goal is simply to capture a fun snapshot for the family, then professional guidelines are not as important. My comments are always based on the idea that you intended to create an image that could be sold as a professional portrait.
You have a delightful subject and you need to be commended for capturing her in a candid moment where her thoughts are about what she is doing. Many professional photographers make the mistake of always trying photograph a child while they are laughing. There is much beauty and innocence to photograph if we simply stand back and let things happen and be ready to capture the magic when it occurs as you did here.
The main issue in this portrait is that you have not created what is regarded in the industry as portrait lighting. The main source of illumination in your image is lighting straight into the girls ear and pretty much misses the front of her face. You have no main light here which is why all of the important frontal features of the face are in shadow. For typical portrait lighting, we light what is called the mask area of the face. The mask represents the frontal features including the eyes, cheeks, nose, chin and forehead. The girls frontal features are largely in shadow because your main source of light is coming from over her right shoulder. We dont usually emphasize the ears in portrait work. We generally light the face so the ear is in the shadow created by the main light. More on that in a moment.
Shadows are not the enemy. I am always startled by how many people talk about removing shadows as if they are evil. Shadows are a very necessary element to beautiful portrait lighting. Eliminating them removes shape and form from our subject. Correctly used shadows create three dimensional contrast which is very important since we are working in a two dimensional medium. Fully understanding what portions of a face are to be lit and what portions are not, is essential to creating portrait lighting.
Again, look at the lovely childs face. Her ear and the side of her face are the brightest parts of her head. For portrait work, there are two ways to light the face for most lighting patterns. Broad lighting and short lighting. Broad lighting adds width to the face and therefore weight to the subject. It also lights the ear if its exposed which is usually a busy object and draws attention away from the more important frontal facial features. Short lighting on the other hand, lights only the important frontal features, leaving the ear on the shadow side, darker than the face so the face remains the most important and brightest area lit. Short lighting is also slenderizing which can be very helpful if your subject has a round face or is a little over weight. This is the reason most professional portrait photographers choose short lighting over broad. Its a more flattering pattern in most cases.
In this case, you didnt use either broad or short. Had you lit her by placing your main light to camera right and lighting into the face just far enough to her left so that her right ear was not lit, you would see beautiful short lighting that lights the frontal features while the side of her face nearest to the lens remained darker, and controlled by your fill light that should always be located near the axis of the lens. The fill light does not go to one side as many would have you believe. I cannot emphasize this enough. If the fill comes from any location left or right of the axis of the lens, then it will make its presence known by casting shadows that conflicts with the structured lighting from the main light. That is absolutely not what the fill lights job is. It is to control the brightness levels of the shadows created by a properly positioned main light. Thats its only job and the only way to do it without making its presence known is if it is coming from the axis of the lens or just above the lens. This is normally an umbrella directly behind the camera so it fires over your shoulder as you make exposures.
Once again, I feel that you are going to do well because you are patient enough to wait for the magic moment to arrive. Once you combine that talent with the use of correct portrait lighting, I think you will exceed your own expectations.
I hope my comments were helpful to you. Feel free to write to me anytime I can help.