If you're planning on selling a product, look for a web host that offers a Secure Sockets Layer (SSL) certificate, because it encrypts the data between the customer's browser and web host to safeguard purchasing information. You're probably familiar with SSL; it's the green padlock that appears in your web browser's address bar as you visit an online financial institution or retail outlet. A few companies toss in a SSL certificate free of charge; others may charge you roughly $100 per year for that extra security layer.
When it comes to server operating systems, Linux is typically the default option. Still, some services offer a choice of Linux or Windows hosting. If you have specific server-side applications that require Windows, such as SQL Server or a custom application written in .NET, then you need to make sure your web host has Windows hosting. But don't let the idea of a Linux host intimidate you. Nowadays, most web hosts offer a graphical interface or a control panel to simplify server administration and website management. Instead of typing at the command line, you'll click easily identifiable icons.
One thing we learned in reviewing the services listed here (and many more) is that even though the packages are very similar, they are not identical. Some are more security-focused than others, offering anti-spam and anti-malware tools. Others offer a variety of email marketing tools. While most of the hosts we've reviewed have built-in e-commerce, you may want to consider using a more-robust third-party online shopping cart application like Shopify instead.