You are good with secrets
If you can restrain yourself and keep secrets of other people from her when you necessarily have to, she might not like it, but she will get used to it eventually and in fact come to respect you for it because, you have shown her that her own secrets are just as safe with you.
You let her know details of your phone
This is easy. A phone without passwords or one whose password is well known to your lady is one of the easiest, fastest ways to earn her trust.
It suggests that you have nothing to hide from her.
