What are your methods for gaining the trust of a target?
Manipulation and deception works wonders.
The trick is to appeal to their interests. People like it when you show an interest in who they are and what they do (of course, without them knowing that your interest in them isn't genuine).
It also helps to not appear threatening in any way. Sometimes even appearing as the victim yourself encourages others to open up and drop their guard down, exposing their vulnerabilities which can then be played on.
How you gain someone's trust depends entirely on the individual, the situation and what you hope to gain from it.