Impulse buying is an easy mistake to make when you haven't planned your shop in advance. Taking a list of the key items you need will ensure you're only shopping for the essentials, and won't be sidetracked by specials or appealing products.

Another common error is blowing your budget. If you're fortunate enough to have a supermarket that provides a handheld barcode scanner to use as you shop, make the most of these devices to give you the running total of your expenses. Otherwise, a simple calculator will do the trick. Punch the price in after adding each product to your trolley or basket. This will help you keep your budget in check and make wiser choices when it comes to selecting products.