[*]Taking lots and lots of shots to get one doesn't cost money with digital - and you will get better also.
[*]Children will react to a pointed camera for a while. Persevere and eventually the camera will be less of an oddity and you will eventually capture shots where the pointed camera isn't determining the facial expression.
[*]Back off a bit. Full face portraits, while possibly attractive, really don't tell the whole story of a child. Backing off will also make it a bit easier to capture the shot.
[*]I believe in the getting down to eye level mantra because I want to see the child as a person in the environment and not mostly his/her forehead. A picture of a child looking adoringly up at you may be interesting once but save that shot until the camera is an expected part of your silhouette, so the child is looking at you and not mugging for the camera.
[*]take lots and lots of pictures.
[*]take lots and lots of pictures
and most important
[*]Try to get objective about your pictures. You took the picture, so you have pride of ownership. It is your child so you have parental love. Other people, except for being nice to you, couldn't care less.
[*]Post your pictures as an example of your work not as 'the best picture I ever took of my child who is the dearest thing in the world to me - and my dying Mother loves this picture.'