Are you currently comfortable with a particular medium? That may be the way to go.
If you want to start with a new figure specific medium, I'd suggest the Vallejo and Andrea lines. They are formulated for brush painting and aimed directly at the figure painter.
IIRC, that's a pretty large figure. If you can get really fine lines with the airbrush, that may be the wy to go, even for shading and highlights, but certainly for the base color, flesh, blue and black.
For Spock, I'd avoid any 5 o'clock shadow, he was always very smooth skinned in he show.
Avoid commercial flesh or at least use it as a starting point to mix a more natural flesh color. My base flesh is Vallejo beige red. I add varying amounts of their game color dark skintone to darken it then their pale flesh for highlights.
This link will give you a lot of information on using this type of paint.