You most likely have a website for your business and if you don't, please give me a call. :-) But now that you have a website, is it working for you? Is it selling to your visitors? The days of the fancy, cool, flashy website doesn't win anymore. It's the one that explains to your customers what they need to hear and lets them act on it.
AIDA is an old marketing acronym that works very well when designing a website.
A - Attention (Awareness): attract the attention of the customer.
I - Interest: raise customer interest by focusing on and demonstrating advantages and benefits (instead of focusing on features, as in traditional advertising).
D - Desire: convince customers that they want and desire the product or service and that it will satisfy their needs.
A - Action: lead customers towards taking action and/or purchasing.
AIDA according to Wikipedia
I read a great post over at Zygote, a blog about web business. They show a few great examples of how websites are designing to sell. They also share a great clip from the movie Glengarry Glen Ross, where Alec Baldwin gives his overview on why the team isn't selling enough mortgages. Here it is, please be aware the language may seem offensive to some, but it does bring up some great points.