The longest part for me [about the process of a piece] is the conceptualizing. I spend a lot of time on the computer sketching in Photoshop, playing with colors and themes. Since I work from photo references I generally draw on top of the photos so I can change the hairstyles, clothing (or no clothing), etc. Once I feel good about the image I'll start sketching it on the wood. Even though my paintings are highly planned out, I leave a lot of room for changes and improvising.
After I'm happy with the pencil sketch, I start with the skin. I guess you could consider my technique more like "finger painting". I like to blend the colors together with my fingers, I find it's a much smoother result than using a brush. (My flesh color palette consists of Yellow Ochre, Alizarin Crimson, Burnt Umber, Titanium White and Ultramarine Blue.)
The tattoos are predominately black watercolor pencil. I know, water and oil don't mix, but somehow the pencil works great on top of the oil paint (once it has dried a little bit). To get the color hues, I mix a lot of paint thinner with the oil so it's nice and transparent. I suppose some linseed oil would work too. If I feel like it needs more definition then I'll go in with my ink to get some darker lines. The mermaid tattoo is inspired by art nouveau designs. The quote says "fair winds and following seas", which is a traditional mariner's phrase, it's like a farewell/blessing. It gives me chills a little bit.
Once I am satisfied with the skin, I start the hair (my favorite part). I start by blocking in most of the color and shape with flat black oil paint. Once the black dries a bit, I bust out my India ink and draw in individual strands, just to give it more life.
For the blue halo, I was in a bit of a predicament. I felt like it really needed it and I wasn't going to be happy if it wasn't there, but it's difficult to get a smooth and even color when painting with thinned-down paint directly on the wood, as it soaks in so quickly. Then I found an old bottle of Bleached Linseed Oil buried in the depths of my art drawers. It adds a nice gloss and transparency to the oil, which made it really easy to use directly on the wood. It's also thin enough where I could paint directly on top of the hair to get the blue behind it.