Which boundaries are negotiable and which are not? Are both parents on the same page?
When is my child old enough to have a mobile phone? Go to the park alone?
Often our own experiences growing up affect our ideas about boundary-setting and whether we want to do it the same or differently. Society has changed as well and children have access to the world via technology.
There are no simple answers to these questions, but talk to other parents and share your thoughts. Safety needs to be paramount, but so does allowing our children to make mistakes and learn. Decide what the non-negotiables are (which will need to be renegotiated over time!) and explain these to your child. Some parents find writing up the family rules to be helpful. Discuss the issues with your child that you are prepared to negotiate on and let them know what behaviours you would need to observe that would let you know they are ready for more freedom. When mistakes are made, renegotiate.
Children are much more likely to respect the boundaries if we are in a trusting relationship with them. This respect is earned from our positive role-modelling and honest communication.