Hi Rebecca,
This painting will be so much fun! There are just a few things to watch out for, as I look at this photo. First, I would drop the horizon line a little so it's on a plance with the woman's eyes. That way it won't present any possible tangent problems, and will help support a focal point. (Norman Rockwell used this convention for many of the Saturday Evening Post covers, during the years when the cover format always consisted of two parallel black lines under the magazine name. Here's an example :
http://www.masterpiece-paintings-gal...wet-canvas.htm he painted.)
Second, when photos have such strong contrast, there is a temptation to fall prey to the "value clumping" that is represented in the photo (that is, the darks are too dark and too compressed, the lights too light, and too few middle tones). To combat this use an overexposed print to located middle tones in shadows, and and underexposed print to (try) find tones in the light. Sometimes, though, there just isn't enough information on the film to get as much as you'd like.