I don't think I could work without layers either! Here's an example (and some fun I was having turning on/off layers!):
Just a demonstration of the different layers I used on the shuttlecraft. Left column has the "lines" layer off, right column on. Alternate rows have the "shading" layer on & off. And the lower half has the "colors" layer on. Separating them like that allows me to change things like color or markings quickly without having to go back and change the color for each side separately due to shading.