I used to hate doing preliminary drawings or any sketching leading up to a final painting, It always seemed so tedious, like I was doing things over.
The truth is I find I am more satisfied with the results when I take the time to explore the image first. One of the reasons why I started to do this was to help me decide which medium I wanted to paint the image in.
I start with a pencil drawing. It helps me to identify and try to solve ahead of time the areas of the image that are going to be more difficult for me. In this image I wasn't sure how I was going to resolve the models right hand. The fingers were in shadow and I had to find a way to make the shape read like a hand and not a stump. The face was also mostly in shadow and I had to decide how much information was necessary and how much I could leave out.
In the color sketch above I was mostly concerned with how I was going to paint some areas cool alongside warmer colors. Like the cool blue along her temple and some of the dark's being more of a violet color and some more of a mixture of burnt umber, burnt sienna and ultramarine blue. More burnt umber or burnt sienna would make the color warmer and more Ultramarine blue would make it cooler. The end result bellow may not be error free but it went smoother having explored so much in the sketches before I delved into the final painting.