John Greim/Getty Images
Buy store brands, not name brands
Generic stores brands are often underrated, and offer similar quality for a cheaper price. You should consider purchasing store brand staple food products (like sugar and flour), which are regulated and often produced the same way that the brand name items are. Paper products, like napkins and toilet paper, are also good to go generic on.
Costco's store brand is called Kirkland Signature (and has been touted as excellent quality), at BJ's it's Berkley Jensen and at Sam's Club it's Member's Mark.