Many children and young people will be using Xbox gaming stations at home and as such Microsoft have put together quite a comprehensive toolkit (a PDF document) for parents, children and young people that goes into quite a lot of depth, including parental controls, guidance for all ages, common safety risks, bullying, unwanted contact and more. There is also age-specific guidance (from 5 years upwards) and case studies.
The toolkit has been produced for gamers in Australia and new Zealand, but having read through I can see no reason at all why this can't be used by any person in any country, the information is all the same regardless.
The link to the toolkit, which is a free PDF download is HERE.