Internet Matters is a website focused on supporting parents and enabling them to receive expert support and practical tips to help their children benefit from connected technology and the internet safely and smartly. They have created a useful parent guide on how to support your child when online:

Parent Guide: Online Safety Tips

Internet Matters also have a variety of other guides and resources that parents may find useful e.g advice on setting controls on different devices, search for advice by age group or develop an understanding of various online issues.

https://www.internetmatters.org/resources/