Sci-fi Pinup

I really enjoy working with monochromatics really for creating a dramatic look. Here I tried to do some figure sketch of a girl presenting an electric scooter. I started first by doing a loose sketch with a 50% fill and opacity and a hard edge brush. Later I began to tighten and soften the image where needed. The 4 dots of color are my palette of colors that forward my range of light to dark with 2 medium tones between. I feel this is a good practice for my skills in figure drawing. I don't seem to do much of it, but I'll give it one more try. But now looking at it I'm thinking it may need some more contrast.