The other day I was booked to take a few portraits of a client's daughter. She wanted photographs which showed her daughter as she is, with her personality showing, not too posed or with forced or fake smiles. She also wanted the photos to be outdoors so we met in the park one afternoon, with rain clouds threatening to ruin the session (they didn't - but driving home I had to stop the car as it was totally bucketing down).
So, who does one get natural, not too posed photos of a child? I wish I had a universal solution to this but the truth is it varies from child to child and it depends a lot on their age too. I generally find that talking to them helps a lot - start the session by just talking and hanging out so I can try to get to know the kid before the camera is even brought out. I also count on the first few photos to not be used - I basically photograph away for a bit to get the child used to the camera and after a little while they are more relaxed in front of it. Sometimes I ask them to just run back and forth for a bit, or around a tree, or shake their heads really hard - anything to get them a bit relaxed and un-stiffen the muscles! I sometimes tell smaller kids to try to see themselves reflected in the lens - which keeps them looking into the camera. I also encourage them to move about and play and I try to freeze some of those movements, so to get some images where they are not focusing on the camera at all. I also encourage kids to be perfectly still, quiet, relaxed, without smiling. I tell them to pretend that they are listening to story or a teacher in school. I do love portraits without smiles - I think a serious/non-smily photo can be really lovely.
With Anna I had no problems, really. She is not too young, so she could be gently directed. And we just chatted away and she told me about her school (term had just started) and she jumped around a bit, and then she just turned towards me and I got the perfect, natural moment. She's a pleasure to photograph - I wish all sessions would be this easy!