Shopping at Costco can save you a substantial amount of money over time, but there is always more you could be doing to make the most of the store's bargains.

Take advantage of low-cost, high-quality gas. Read the price labels carefully and choose the store brand for big savings. On Sept. 1, Costco raised the cost of its membership fees for the first time in years. Now, a Gold Star Costco membership costs $65 per year, while an Executive membership costs $130.