Stay ‘on grain’! If you don’t, the fabric may sag or pull. And the ‘nap’, watch out for the nap! The short fibers on the surface of a piece of fabric is the ‘nap’ and depending on which direction it is lying, it will reflect light differently.
I needed a skirt to go with a new jacket I’m working on. I wanted it to be a solid color with a subtle but bold geometric design. So, with structure underneath [to stop any sagging or pulling], I laid out pieces of a silk dupioni going up, down and sideways. Can you see how direction of the nap shows off the shapes?