Things to avoid: Hiding information and creating barriers.

A common problem with web sites designed to sell a product is the practice of hiding information behind barriers. This can occur in a number of different ways with the most common examples being:

• Contact a sales rep: By far the most common barrier put up is to hide information on pricing, packages, or many other product details by simply shunting users to a contact a sales rep form. The reasoning behind this varies from hoping the sales rep can sweet talk someone into a sale to trying to hide information from competitors. However, in almost all cases it is simply better to be as up front with potential customers as possible. Ideally when a sales rep takes a call or an e-mail it is not to answer a question, but to process an order.
• Requiring a login: Once a user has started down the sales path it is entirely acceptable, and often necessary, for the user to have a login. However, before the user has gone down that path, when they are just browsing for information, it is a mistake to force them to create an account just to view the web site. This only tends to be an issue with new sites that have not had a chance to mature and realize the user drop off that is occurring at their create an account page.

Not hiding information and instead being upfront with it is beneficial for many reasons. Firstly, search engines love to index information. If you have obscure packages tailored to a particular niche then list it. If you have model numbers for products then put them up. All these things get searched for eventually and it is easier to rank for uncommon terms than it is for the common ones.
 
Secondly, customers like to buy with confidence. The entire design of a site should be focused on instilling a potential customer with confidence and making it as easy as possible for them to click on the buy button. Any obvious information that the customer wants, but cannot find, detracts from their confidence. Forcing them to switch from browse mode to interactive with a salesperson is a barrier. Burying pricing details too far into the process is a barrier. Not being clear about what is offered is a barrier.