The first mistake most entreprenuers make is hiring a great graphic designer to design their site, without finding out if the designer has any idea how to market. The consequences are all those sites that aren't making any profits, even though they may have cost thousands to produce. However, you can do it right the first time and hire a marketing specialist and the rest of the team to design not only your site, but your entire marketing and promotion, so that you are assurred of being successful the first time out. Creating a site that sells takes expertise not only in design and programming but in marketing and sales.
Online sales are very different from sales offline.
The offline model of advertising of concentrating on emotional appeal has to be combined with hard information online to satisfy your prospects and customers. The lack of face to face contact is not as insurmountable a challenge as it might appear, but it does present a definite challenge. Your website is your online business presence, your store front, your major identity online. The importance of an attractive, easy to navigate, interesting site cannot be stressed enough. It is not enough to simply have a brochure online.