Buy what YOU like. It will be easier for you to be excited about the fabric, maybe make some samples using it, and promote it to your customers. Then as you grow, start buying what customers ask for and you do not have. Blenders are always good fabrics to have - all colors but especially whites, off-whites, and beiges. Baby and toddler fabrics seem to be popular here too - they can make quick and easy quilts - some panels too. My favorites are blakc,red, and white - but these are not that popular with most people. Wishing you the best of luck on your new adventure!