I used a small (about 2mm) drill to create pilot holes for the F-holes. I first created a series of dimples with a sharp pencil, both to make it obvious where to place the drill bit, but also to discourage the drill from wandering. It worked quite well in both regards.
Cutting out the remaining material with a sharp utility knife was more challenging. At the ends of the F holes it's difficult to cut the spruce without breaking out the delicate ends. I had to reinforce two of them with a bit of white glue, but overall the shapes are pretty good. I still need to clean up the edges with fine files.