There are many ways to accept payment for goods or services via your web site. The right answer depends on the nature of your site and the size and frequency of the payments you expect to receive from customers.
If you do not expect to take thousands of dollars in orders every month right away, or if you are not ready to invest roughly $100 up front and numerous hours of your time in opening a credit card merchant account and obtaining an SSL certificate for your own secure web site, you should definitely check out PayPal. As of this writing, PayPal is by far the easiest way to start accepting payments for purchases of goods or services via the web. Everything you need is provided, including "shopping cart" pages and "buy now" buttons. You do not need to learn any sophisticated scripting. PayPal allows your customers to pay by credit card or check, and many of your customers will already have a PayPal account, since PayPal is the preferred payment method on the EBay auction site. In fact, using PayPal can increase the chances that your customer will regard your site as trustworthy and choose to do business with you.
I have no affiliation with PayPal, except as a satisfied client; my own customers are given both options: use my own secure store and merchant account, or use PayPal. Those purchasing less expensive items often choose PayPal.
For those who are processing orders on a larger scale, or who must also be able to accept orders by phone, fax and postal mail, it may be more cost-effective to obtain a credit card merchant account. A credit card merchant bank clears the transactions for you and deposits them within about 48 hours to your company's checking account. There are usually monthly minimum fees, in addition to a percentage of each transaction, also known as the "discount rate," and typically a small per-transaction fee as well. You will also need to set up a secure web server, such as the freely available ApacheSSL server; you can arrange this through your web hosting company, but you will need to pay an annual fee to an SSL certificate provider for an encryption key which proves to web browsers that you are who you say you are. Without this key, your users will not see the "lock" icon in their browser that is widely considered synonymous with safe online shopping. And, of course, you will need to greatly improve the quality of your web server's security if you plan to pass other people's credit cards through it; companies have been blackmailed more than once by hackers who have obtained customer credit card information from poorly secured sites. If this sounds like too much work to do right, arrange for a consultant to do it, use the services of a company like The Processing Network that provides PayPal-like web services for those who do have merchant accounts, or use PayPal.
