Some websites and programs to help your children stay safe online:
Snapchat - a parent's guide - read more here
Best source of advice on staying safe online in Ireland
You can also install apps on your child(ren's) phones and tablets to monitor and/or limit what types of internet access they have. There are many product reviews online, such as the one here, or search for e.g. best parental control apps.
Keep your personal data safe. Download tips for safe online banking, Facebook, passwords and more...