First step I take with any oil painting is to cover the canvas. With this painting, I actually covered the canvas with acrylic. I like to use acrylic for this stage because it dries fast. and mostly I try to get the major shapes in (i.e. shapes of the shadows, highlights, etc.). Goal is to get things as quickly and right as you can without sweating the details.  

Now I approach with oil, really trying to get my smooth transitions. Making sure I'm getting good values and getting the general feel form that I want. I only touched the subject, leaving the hair, and background untouched. 

I now come in with some detail. 

Shadows - Smoothed out the shadow on the left cheek, added some definition to the lips, nose, and chin. Some updates to the eyelid area. And darker shadow on the shoulder. On skin this color I like to use purple to darken the tones for the shadow. 

Eye lashes - I made sure to do that once I felt good about the eye lids, to avoid having to work between the eyelashes.  

Really went in with lots of lines. Used a thin brush (like a small round or liner) to individually draw hairs in. I also wanted to capture the stray hairs which I think make the piece more interesting. 

For the eyebrows I both added some individual "black" hairs, but also used some of the skin color and painted that over the black eyebrows.