How to convince users that my website will not sell their personal information to other parties?

Allowing some transparency and providing clear information about what the company does or doesn't. Also giving users the option to tick box or confirm or disagree with some of the information provided so that whether or not the users want to proceed is entirely up to them. Having other company or law information such as data protection act or breach of confidentiality. Users should feel safe and in order for this to happen, company must either take necessary steps to show with the effective use of terminology and logo or option to allow or disallow information to selected3rd parties. Being clear and stating why under what grounds and laws doesn't the company allow the selling of personal information. Giving users the confidence is a key factor.

We deeply committed to respecting and protecting your right to privacy and takes your privacy seriously. We strive to keep your personal and financial information secure. Our privacy policy disclose and describe our information gathering and dissemination practices for this website. Most of all, we value your privacy. We do not sell, rent, loan, or give your email address or other personal information to anybody without your express permission.