If you don't see a little lock icon at the bottom of your browser window, don't click the button that sends your credit card info. You should expect any online store to be secure. Word of mouth is your friend. If you're not sure what shopping sites to start with, ask your friends and family. If you're not sure which shopping sites to avoid, ask your friends and family.
Recommendations are a great source of information on and off the Web.
Most shopping sites let buyers review products. Customer reviews are generally right on target and can help you avoid spending money on a bad product. Shop frequently at sites that offer reviews, read the reviews, and be sure to contribute to the reviews if you have some insight into a product. I like it because it seems to have the broadest coverage of products. Simon Similar to Jango, and covers books, clothes, computers, electronics, flowers, food, toys and several other major shopping categories.