I usually find a pattern first or go with a theme and look for fabrics from my stash that might work. I make lots of small quilts for monthly challenges for a small group I'm in. These don't require lots of yardage, generally. If I don't have something I need and can't paint or dye it, I'll go to the store. Lots of times I'll make a mock up of the pattern block by cutting fabrics and gluing them on the paper pattern, to test fabrics. Or if I know what colors I want, I'll just use colored pencils to color the block and then once that's decided look for fabric to represent each of those colored sections. I know it seems confusing, since there's so many choices: prints VS solids for one. I mix up my prints - use Batiks and large and small prints, blenders, hand dyes, etc. I think it's more interesting that way. Some people find a designer or fabric line they like and just use fabrics from the line that go together. That might be a way to start for you. Whatever you do, enjoy the process. This is FUN!