• If you see that your customers are all middle aged or older, think about type size. Make sure your text isn't isn't too small or difficult to read.
• If you have a primarily male audience, you have to think about color-blindness. If you are working with women, you don't have this concern.
• If your audience is younger, maybe you should have less text and more graphics (including Flash content).
• If your audience is likely to spend money easily, put a special offer on the front page of the site. If they are the thrifty sort, make the special offer a reduced-price special offer.

Even after you've considered the demographics and propensities of your likely audience, put yourself in the shoes of the business store clerk. Consider, for instance: where you would put the "on sale" items? If you open your eyes and get out of your technology-elite perspective, you might find out something about your audience and it just might surprise you.

How about an example of good design and great usability? One site I like is Joann.com, which is a chain of fabric stores. They have large type, easy navigation, and lots of specials. When I go into the physical store, the customers are predominately women who are 30 years old or older. Many of them shop there to make things for their kids and grandkids. Not that many of the customers are likely to be computer literate. That's my impression, at least, derived from talking to people while waiting in line. What I'm particicularly impressed with is the way the Joann.com website has loads of specials and features that tie in perfectly with their physical stores. The customers in line at the checkout stand talk about the website and how they check it weekly to see what is on sale.

Test your site with inexperienced web users
Never overestimate the lowest level of users who visit your site. Usability testing is one of the most important things you can do when rolling out a new website. When you have your site mocked up, test the design and the flow of your navigation with someone who knows nothing about the web. Don't look in your own circles. Reach out. Ask one of the coffee-servers at Starbucks. Check with your mom. Ask a local librarian. Check with the receptionist where you work. Not all of these people are going to be representative of your website's anticipated clients, but they will look at your site with a set of eyes that are a lot fresher than yours.

Do not discount anything these not-so-web-savvy users say or do. Don't just rely on them to tell you what was wrong—be there when they access the site for the first time and watch them as they browse around. Watch, especially, where they hesitate. See what they look at. Listen to them talk to themselves. In fact, urge them to talk out loud while you watch. The feedback they offer as they natter along is very useful.

Specifically focus on whether they identify with your basic navigation of the site. For instance, let's assume you have a clothing site and your navigation has an initial split between men's and women's clothes. Pay attention to whether this division makes sense to your first-time users. If you observe them looking for trousers or blouses or shoes before they make the men/women split, then you have made their experience one click more frustrating than it needs to be.

Test early and test often. Fixing things at the beginning of the design process will be five to ten times less time-consuming than redesigning a website after production.