Adults have complete knowledge on how to handle such situations and according to them ignoring is the best way to get rid of this hassle. But if your child is stuck into such problems then you have to figure a proper idea with the help of which you can make your way out of the hassle, because sometimes children avoid sharing such problems with their parents. Try taking your child in confidence and on daily basis ask him or her about his daily routine and what sort of activities is she or he involved in.
If your child is an internet user than try notifying them that what sort of information should never be shared with strangers. Make them understand that what kind of friends are capable of being trusted that you can share your photos, and who are not.
Secondly explain them in detail the advantage and disadvantage of using social network sites, whom should be added into your circle and whom should not be.
If your child has a cellular phone then tell them not to reply any unknown number or reveal any information which might get misused. If any prank call is disturbing you then block the number right away or ignore it.
Do not reply any of the mails video clippings or text message no matter how rude the message is which you have received.
Sometimes fake prowp-content/uploads are also made in order to bully others which make the situation more worse.
Try suggesting your children to avoid using chat rooms because you will find various unknown people whom you are not aware of.
Keep your passwords and usernames safe, along with your mobile numbers.
Internet can be accessed in cell phones besides computers so, it is better to install internet safety features like anti-virus software etc.