Shopping online already offers many advantages -- no crowds, a wider range of products, and the ability to hunt down the best price if you're after a particular item. It also has another advantage that isn't easily replicated in real-world shops: the ability to use promotional discount codes to reward regular shoppers or attract new buyers. Bargain codes can be a great way to save money, but a little caution is often sensible.
You can come by bargain codes in a number of ways. Many retailers send them out as part of their regular mailing list, so if you've signed up for email updates, you're likely to receive information for discount offers. The other predominant source is online listings. OzBargain is probably the most visible local site specialising in tracking down online discount codes (though it also has information on real-world store discounts). Codes are usually entered during the checkout process. If you can score the right price, discount codes can make a good deal even better. However, beyond the obvious reminder that it's not a bargain if you didn't need it in the first place, there's a couple of key rules to bear in mind in this regard.
Check if the code is tied to a particular buyer
Some discount codes can be used by anyone; others are specifically tied into a particular account, and sharing them around probably won't work. This is normally pretty self-evident. If a code is something like XMASBARGAIN, it's likely to be universal; if it's a complex sequence of letters and numbers, it may well be restricted. Some codes aimed at rewarding existing shoppers are also designed not to work with newly-created accounts, though there's no way of being sure of that until you go through the purchase process.
If the offer looks insanely good, it may well be withdrawn
It's not unknown for vendors to disallow the use of codes if a combination of options results in a particular item being insanely cheap or even free. Sometimes this is defended on the grounds that codes aren't meant to be used by multiple people; sometimes it's clear that someone in the store screwed up and didn't think through the consequences of a particular deal, or simply posted the wrong price by mistake. Some vendors will honour such mistakes for anyone who completed a purchase, but others take a harder line. The OzBargain blog offers a recent cautionary example in this regard, noting that Wishlist.com.au has twice created deals in recent months that effectively allow people to order free movie tickets from the site, and has twice cancelled those offers even after people have placed orders. A little Google activity to check out the reputation of an online seller is always sensible, even if you're worried some uber-bargain might sell out.
Double-check the details before committing
In the excitement of finding a good bargain, it's easy to miss vital details -- such as the claimed discount not actually being applied, the postage rates being insanely high, or the terms and conditions including a commitment to buy further goods. By the time you're entering payment details, you should be very sure that you're getting what's advertised. Lifehacker's weekly Loaded column looks at better ways to manage (and stop worrying about) your money.