I thought I'd share my answer to her as it may be of interest to others.A few years ago I purchased Richard Schmid's book "Alla Prima, Everything I Know About Painting". It is available from his website. I have read it 3 times now and it is by far the best book that I own. What I find interesting is that each time I re-read it I'm at different stages as an artist and I am able to understand concepts which earlier seemed vague. I love the unfinished look of a painting by artists such as Richard Schmid, Nancy Guzik, and Carolyn Anderson. One of Robert Genn's Twice-Weekly Letters found here praises the technique.
I want my paintings to draw the viewer in with hints of background and unfinished areas - I think it makes for a more interesting painting.
I'm working on a painting using another reference from photos that we took on our San Francisco trip. I'll post a work in progress tomorrow.
Have a great weekend!