I hate paying more than I have to for anything, but there are so many sites out there that either make you fill out a lot of personal information or download something in order to get coupons. These are some sites I found that make it really easy to be cheap without having to cut coupons or buy cheaper versions of what you want.
Priceblink: you can download this as an add-on for your browser and it will alert you whenever it finds a lower price for the item that you are currently looking at. This is great for expensive items, because you can find the lowest price or you can tag it and Priceblink will email you when the price is lowered to your price range.
Amazon's been around forever, but it really can't be beat. They almost always have the lowest price, you can get free shipping if you spend enough, and they deliver fast! Since I get a lot of items from Amazon (gifts, household items, cleaning supplies, pet supplies, and more), I regularly add the items that I know I will need to my wishlist, and then I filter my wishlist to show only items that have recent price drops. Then I wait until the price is within an acceptable range.
You should also click on Today's Deals on Amazon's Main Page. There you will find low priced items, but you will also find coupons. All you have to do is click on the coupons for the items you might want to buy, and then when you add that item to your cart it will apply the coupon automatically. The coupons last for awhile too, so you don't have to buy the item right away.
If you have a Kindle, you can also add eBooks that you want to your wishlist and wait for the price to be lowered. If you are just looking for something to read, check out their free books. They change regularly and are ranked, so you can find books from lesser-known authors that have 4 or 5 stars and get them for free. I have found some great authors this way, and have gotten to read many books for no cost at all (and without having to travel to the library). If you follow @amazonkindle on Twitter, they tweet links to free books and books that are marked down to $1.99 every day. All of the tricks I just noted for Kindle also work for mp3 albums that you can purchase and download on Amazon.
If you love to read but have trouble finding appealing books, check out Goodreads.com. There you can rate some books so that they give you recommendations and you can join book clubs with people that have similar interests as you. The site also lists Amazon prices for the books, so once you find a book you want, you can purchase it on Amazon.
If you have other suggestions on how to save money doing online shopping, I'd love to hear them. Feel free to enter a comment or contact me directly!