Guangzhou is amazing! I was there (again) last week and went to the Fabric and Accessories Wholesale Markets using the subway.
How to buy your favourite fabric? Well, choose the fabric from the displayed samples and do the payment. They will ask you to wait for one hour. Why?
They need time to get your fabric from the warehouse which is located quite far from the shop. And most of them are using bicycles. So, while waiting for the fabric, you might want to visit another shops. But remember, each time you decide to buy a new fabric, then you have to wait for another one hour. The market will close around 7 pm, so please stop shopping at 6pm (^_^)