Key principles for all age groups include:

Keep lines of communication open.

Create a list of Internet rules with your kids.

Set parental controls at the age-appropriate levels and use filtering and monitoring tools as a complement--not a replacement--for parental supervision.

Supervise all Internet-enabled devices and keep computers in a public area of the home.

Encourage your kids to come to you if they encounter anything online that makes them feel uncomfortable or threatened. (Stay calm and don't blame your child; otherwise, they won't turn to you in the future for help when they need it.)

Teach them not to interact with people they don't know offline, because an online predator or cyberbully can disguise him/herself.

Check the history file on your computer to see which sites your child has accessed.

Teach your child the golden rule: do unto others as they would have done unto themselves.

From: https://internetsafety101.org/agebasedguidlines

Websites for Parents

NetSmartz

NetSmartz offers free, multimedia Internet safety presentations tailored for specific audiences – parents and communities, tweens, teens, and younger children.

Be Internet Awesome - Google

Be Internet Awesome is a multifaceted program fro Google that includes a fun and free web-based game called Interland and an educational curriculum to teach kids how to be safe and responsible explorers of the online world.

Common Sense Media

Common Sense Media improves the lives of kids and families by providing independent reviews, age ratings, & other information about all types of media.