Ditto on the gesso. (that’s fun to say)
It dries quick, sands well, fills some gaps, is cheap, and the contrast of white to the blue or pink of the foam helps show coverage. Two coats for full coverage depending on surface finish, and then you can go back in with spackle to buff out the form. When I was a lowly junior designer I did many many models this way (google 'Snell CLS.5)