I think Chris posted the above reference to me to be nice, and because she knows I am online tonight.
Go look at her website! Also look at the websites of Michele Rushworth, Tom Egerton, Peggy Baumgartner, Linda Nelson, Brian Neher, Dawn Whitelaw, Burt Silverman - just a few of the different lighting styles in outdoor work.
People love seeing paintings of their children outdoors, especially in warm-weather climates. But in my opinion it is hard to be really good at outdoor portraits, which is why there are so many ho-hum ones out there. The challenge is in finding the form in the unlit side of the face where all the planes are in the same value range; usually, it's best done loose and impressionistically, but the paradox is that then you might lose specificity of features and the individual child becomes the generic "blonde boy in the sun". Generic paintings are wonderful, but in portraiture you should be able to pick out an individual child if you were presented with a lineup of similar children.
When you are painting objects in indoor light situations you are painting things you can touch; when you are painting outdoor light situations you are painting things separated from you by the air and the wild outdoors. It's not "about" touch, it's about freshness, color and light. (I didn't come up with this idea myself, Harold Speed says this in one of his books.)
I am also experimenting with shooting subjects indoors and placing them outdoors but I don't think I'm doing true "realism" when I do this.
Anyway, I am a big fan of outdoor backlighting (there is a thread here on the Forum dealing with this). Place your blonde subject against a dark bush and you'll get a dramatic halo of blonde hair. I also did a photo shoot yesterday of a little boy standing in an open doorway facing the outdoors and I really liked the way it turned out.
Good luck and let us know how it goes for you!