I've been trying to experiment with a few new techniques recently (literal translation = I've been making a mess). For this picture I tried out ink relief, where you use gouache paint to resist india ink on canvas (I found a pretty clear, unfussy tutorial about it on Craftsy). It gives a patchy, painterly effect that I really like.
I'm quite pleased with it. She's got the look of a ghost about her, which seems to fit.
I made another portrait of her a few weeks back, a linocut, which I don't like as much but it's interesting to compare the two.