Nielsen Norman GroupEvidence-Based User Experience Research, Training, and Consulting
There are many tactical elements that contribute to the success of a website, but ultimately, the characteristics most successful sites have in common are the ability to establish credibility and to persuade users to take desirable actions. The nuances of appearing credible and being persuasive vary considerably depending on sector, target audience and offerings.
NN/g offers several courses at Usability Week that address the factors driving perceived credibility and the ability to persuade:
Should you say who wrote the content on your site? Sometimes yes (for credibility), sometimes no (for brevity). And rarely in mobile.
Giving money on charity websites is 7% harder than spending money on e-commerce sites. Donating physical items is even harder. For non-profit websites, social media is secondary; the top priority is to write clearer content.
Different traffic sources imply different reasons for why visitors might immediately leave your site. Design to keep deep-link followers engaged through additional pageviews.
The best way for e-commerce sites to increase subsequent orders is to treat customers well after they place their initial order.
Review of B.J. Fogg's new Persuasive Technology book, which provides useful principles on how to think about creating persuasive design, but rarely gives detailed design guidelines. The exception is a section on enhancing website credibility.