Do lots of research before you purchase any products over the Internet. Make sure that the company you purchase from has a telephone number and address listed on the site. Call and talk to a customer service representative or send the company an email and see how they respond. Look for a money back guarantee and don't be fooled by companies that offer a double-your-money-back guarantee. Check with BBB and other consumer sites to see if the company has had any negative reports filed against them.