What is the quickest way to get people to trust you?

This answer leans more toward business than personal but works for both.

If you are fair with other people and always looking for ways to help them, you will have no problem getting people to trust you.   Don't associate with liars, thieves, or people that have qualities you don't want, or trust.  I believe this bleeds through and most people can read it.  Some things that are important when gaining trust quickly are:

 

• Keep good eye contact at appropriate times. When I worked for a large, successful corporation, I asked the man who hired me (a 30 veteran in hiring) what was the most important quality he looked for in new hires.  He told me that they could hold good eye contact.  Usually people that can do this have nothing to hide. 
• Be selectively vulnerable.  It's not important to do constantly, but it shows you are human, a real person just like they are and is an indirect form of common ground, creating rapport. 
• Work very HARD.  Most people that find out through your actions that you are a very hard worker, will trust you and even refer or recommend you to others in a business environment.  People who go out and make a living through hard work are not generally seen as trying to "get over" on others.  They are willing to put in the necessary effort to earn what they receive.  Still work smart, but work your ass off.
• Be unselfish and thoughtful of others' position in your actions.
• Don't be deceitful.  Basically, be the kind of person others should trust.
• Expect and have faith that they will trust you.
• Be flexible, patient,  and don't pressure them.  People immediately raise their guard when being pressured.  If you release your concern about the outcome, ironically you are more likely to get what you'd rather have.

http://www.quora.com/What-is-the-quickest-way-to-get-people-to-trust-you