Buying at the Last Minute. Online retailer Amazon.com, for example, offers free shipping on orders of $25 or more. The catch is you need to give them a few days to get your purchase to you. Only two days left? Shipping on a single hard-cover book bumps up to nearly $12. Need it tomorrow? Now you pay $18—or nearly the cost of the book itself. Planning ahead can save you a bundle in shipping costs.

Not Reading the Return Policy. Buying some shoes online with the idea you can always return them if they don’t fit right? Then make sure you understand the retailer’s return policy. All policies are definitely not created equal. Read the fine print if you think you may need to exchange or return an item.

Ignoring The Receipt. Online retailers are a lot like brick-and-mortar sellers – sometimes, they make honest mistakes. But those errors are easy to overlook if you don’t check to see what you’ve been charged for. Make sure you’re not paying for unwarranted surcharges or extra items you didn’t order.