Ultimately our relationship with the people who use our applications is built on trust and we want to give them an application that they are comfortable using to handle sensitive data.
Uptime is vital
We should target 100% uptime, 24/7/365. Users intrinsically trust a product which is reliable. Other issues will always be in the context of whether a product is available when s/he needs it.
Focus on data integrity
There is no greater way to erode trust and confidence in our product than for data to appear inaccurate or out-of-date. Ensure features clearly communicate what is happening at all times, especially during errors.
Conveying security is top-of-mind
Our users trust us with some of their most sensitive data, we should take this task seriously. We should make use of iconography and language that reassures the user that their data is secure, including encrypting traffic with SSL so the user’s browser displays a trust-boosting green padlock, for example.
Reduce bugs without sacrificing speed or innovation
A stable product breeds additional trust with the user, so we should focus on user testing, automated testing, and widely releasing product features only when they are perfect (rolling out features to a subset of users can help you find bugs/areas of improvement before a wider rollout).