I doodle. Often I will print a picture of my quilt and doodle using either tracing paper and pencil or transparency film and dry erase markers. My favorite places to go for inspiration is Google and I search the images for something similar to what my quilt looks like. Pinterest is another great place for inspiration.
You can also take clues from your fabric. If a large print, you can go around the designs. Soften an angular design with swirls, etc.