There are several easy ways to build this trust. First, you should put a biography or yourself or your company onto site. You can make it a personal or professional bio. On my site I use a personal biography. It tells:  Where I graduated from college  What my major was  My past careers  Sports and hobbies I've been involved with  My current interests  And my experience relating to products, services and topics of my site

If you have anything on your site that's date sensitive, such as a sale, promotion, coupon or similar items that have expiration dates, then remove them when they expire. I had a friend who used her website to advertise a sale she was having at her store. The ad filled one entire page. Well, about six months after sale had ended I went to her site and found sale still listed. She did have an expiration date, which was a good idea, but also caused some problems.

By leaving this expired ad up it caused some problems with a few clients. Some people came to her store expecting discount mentioned in ad, and became upset when they found out sale was over. Some people became so upset that she gave them discount anyway.

While this solved immediate problem, she still had unhappy customers. These customers no doubt told all their friends about unprofessional way store was run. There's no way to prove it, but I'm sure she lost sales from these unhappy customers spreading their unfortunate experience. Also, you have people coming in that when they find sale has ended feel cheated, stupid (Jeez, I didn't notice expiration date), embarrassed, and all around unhappy. They then try to funnel all of these negative emotions onto storeowner, or whoever happens to be behind counter. Now you have owner and employees feeling unhappy. It goes on and on. All because owner didn't remove page or update it with something like, "I want to thank everyone who made sale such a success. Keep checking back to see when our next sale will happen."