In the age of 3D printing, analog modelmaking is a bit of a lost art. But it should not be forgotten. Sometimes the smartest way to put together a model is to make something with your hands and not with a computer.
Lucky for us there are tons of resources out there including a series of videos from Industrial Designer Eric Strebel. The videos run the gamut from rendering with markers, to making 3D mockups with blue foam, to resin casting, to photo tips for product shots. Check them out here