The Solution
The web gains credibility with each passing month. The cost of doing business online is coming down. A web-ready computer and the associated software was a couple thousand dollar investment two years ago, but is now less than $500. Being online is about as standard in America as owning a VCR. Maybe even more so- haven't checked the statistics yet today. The number of those online households that make purchases online is growing even faster. If you sell to businesses, you're even better off than that. While renovating a lot of their systems to become Year 2000 compliant, a lot of companies became not only internet-compatible, but internet driven- and were exposed to concepts like online ordering of supplies, which saves significantly on processing time.
Unfortunately, there is still a lot of trash and controversy in the "Wild West" atmosphere of the Web. Here are ways you can set yourself apart from the fly-by-nights:
Run a Legitimate Business
If you don't provide something of value for your customers, you may make money, but not long term. Web customers communicate by e-mail and in discussion groups about companies they've been "taken" by. Most web customers can see through overblown promises and failure to meet expectations. If anything, err on the side of understating the value you provide for customers and let them be pleasantly surprised. Your business may grow more slowly, but the relatively few customers you make at first will be loyal supporters. Their references will be worth more than raking in dozens of unwitting customers who will regret doing business with you.
Do What You Know
Don't hold yourself out as an expert in the most popular and lucrative field of the moment if you are not. Since the popularity of St. John's Wort, (an herb that is purported to have antidepressant properties and is also used in weight-loss formulas) for example, the number of sites claiming botanical expertise has skyrocketed. If your expertise is in finances, for example; don't run a web site where you claim to be an expert in fitness and exercise. Just because you have a "virtual" business, there is no substitute for "actual" expertise and credentials. It is illegal to claim to be a medical doctor, attorney, or realtor for good reason. People have been harmed by incorrect or incomplete advice offered by incompetent "experts" who take client's money and provide professional services that they are not competent to provide.
Be Consistent
Although you may be "doing what you know" with several different topics, it is not appropriate to have a vastly mixed or varied topic set. "Jane's Visual Basic Programming Service and Antique Shop" is probably not likely to be as successful as a business that focuses on a single item, devotes all of its energy to a single focus and does it well.
Identify Yourself
Following on the heels of the last suggestion, customers are much more comfortable if they know the person they're doing business with. The more information you can make available to them the better.. It's a good idea to post an "about us" page that describes who you are and why you're in business so that customers can get a better "feel" for the people they're doing business with. Even pictures and personal interests may be appropriate, depending on the context. People probably don't want to know what their banker has for lunch every day, but knowing that he's an avid fisherman on weekends may help build rapport and help make the relationship more "real."
Provide Secure Services If You Take Money (Or Other Personal Information) Online
Ensure the software you use is reliable, and provide information on what
it is and how it works (in plain language used by human beings, not propeller
heads, or as close to it as possible) on your site. If, heaven forbid,
your site is hacked or your security is compromised in any way, publicize
it to your customers before they find out the hard way so that they have
a chance to take action to protect their credit cards. Do everything you
can to assist customers in tracking their orders and ensuring they are
accurate and that their information is secure.
Conclusion
Trust is a significant contributor to the success or failure of any business, brick-and-mortar or virtual. Having a virtual business does not excuse a business owner from any of the factors of credibility, in fact, he must work harder than his brick and mortar counterpart to ensure that his business is seen as real and credible.

