Some things I just make up as I go. But for custom designs I start with a mood board or inspo-images, both from my client and from images I choose. It's good to keep the end-use and target customer in mind because a print a teenage girl would wear on a bathing suit may not be the same print a middle-aged man would wear on his pants. Or maybe it would. :)
A design can start from anything - a painted brushstroke, a photographed texture, or from purely digital shapes. Regardless of how I start a design, it usually ends up in Photoshop or Illustrator and I make all kinds of changes to it - combining it with other motifs, changing the
colors, the scale, or spacing. When I like the design and my client approves it, I move on to creating the files and instructions the factory will use to print the fabric. It depends how it's being manufactured but most designs need to be in repeat - so it can be printed indefinitely on yards and yards of fabric. This part can be super technical, and I like geeking out on all the repeat measurements and guidelines. We also choose Pantone color standards to make sure it's printed the way we want it to look.