Stanford’s Guidelines to Web Credibility:
Make it easy to contact you.
A simple way to boost your site’s credibility is by making your contact information clear: phone number, physical address, and email address.
This is a pet peeve of mine, going to a website and not finding good contact information. Web forms are great, but there really needs to be more than that. Give your visitors multiple ways to contact you. Phone number, physical address and email address are all necessary. I suggest that you make your phone number visible on every page, and get an 800 number. Having a toll free number let’s visitors know that you’re willing to give a little to get a little.
When it comes to ecommerce sites, I personally won’t buy from a store that does not have visible contact information. With so many less than reputable stores on the internet, I often won’t purchase from a store until I have talked with someone via email or phone. If this information isn’t readily available, many sales may be going elsewhere.