- Show that your business is genuine with photos of your offices. Smiling stock photos hurt more than help.
- Make it easy to contact you by listing your phone number, physical address, and email address.
- Look professional by using a professional design that matches your brand's image.
- Make your site both easy to use and useful to reward visitors. (Forget about flash.)
- Keep your content fresh to show that you care. (The easiest way is with a Twitter widget.)
- Avoid having ads on your site as they annoy users. When writing, try to sound sincere instead of promotional.
- Avoid downtime, typographical errors, and broken links.
Source: Fogg, B.J. (May 2002). "Stanford Guidelines for Web Credibility." A Research Summary from the Stanford Persuasive Technology Lab. Stanford University.