1. If you find a great product on the favorite site, search for it in an internet search engine before you buy it. Make note of the model number or brand, and do a quick search to successfully can't obtain it cheaper from somewhere else. You might be able to save a few dollars like that.
2. Although it may look tedious, ensure you read the contract and terms before you purchase at a website. These documents have valuable information on what you can and cannot do when you have an issue with the item that you bought. Read them thoroughly in order that you do not have an unwelcome surprise when trying to return items.
3. Ensure that you're entering your payment details on a secure site. Look for "https://" in the URL in the site that you're attempting to buy something from. If you don't see that or no symbol of any website security, then it's probably a good idea not to trust those people together with your account information.
5. If you want to buy books online, you'll get a better deal if you get them used. Based on the condition you receive them in, you may just end up paying a few cents plus shipping. Make sure you go through the description of the book to see if there are any damages you should be aware of.