Whatcha Lookin' At?

Last day in Sydney so what better way to spend it then with my 6 week old niece! Isn't she just adorable!! I didn't realise just how difficult it is taking a portrait of a baby because they like to wriggle about and most of the time she isn't really exposed to much sunlight (understandably so I guess) so getting a good shot did prove challenging. However when my brother changed her nappy in her nursery room I seized my opportunity. Her room receives excellent light and lying down on her 'changing bed' made it so much easier to take that 6 week portrait.
I just love her, 'Whatcha lookin' at" face!
Does anyone have any advice on how to take excellent baby portraits?