I don't know that it matters so much which order the elements are gathered. I started by photographing large stacks of boxes found in our receiving department at work. The key is to take as many shots as possible from every possible angle with the widest possible field of view. With a digital camera, you can never take too many photos. It's nice to have many options to work with because it's easier to delete and crop material than to create it from nothing or find out more photos need to be taken. I ended up taking 16 shots and used two of my favorites (shown above).
One might wonder, "What are the boxes for?" Well, this was an element I didn't include in my junk sketch, but I intended to show huge stacks of boxes behind the store shelves because my goal was to represent vast amounts of canvases ready to go out the door for this blowout sale.
Notice how the color and angle of the two box shots don't match at all. Since these boxes were intended for a small background element, I decided not to spend much time correcting this. Perfection is not necessary for small-scale projects like this.