There are various types of these scams. I will explain a few.
Many Social Media Sites such as Skype, Kik, Facebook, Pof, Craigslist, okcupid. Badoo and Chatroulette are a home for Scammers and Thieves to use to scam by using threats of fear and/or criminal charges.
This scam involves 'grooming' a potential victim into sending compromising photographs/video to the scammer - In some scams the scammer/thief will, initially, send compromising pictures which he/she will say are of him/her -- these will be stolen from elsewhere
Types of blackmail/sextortion scams:
Threatening to send your images to your Facebook friends and family.
Scammer will meet you on a social media site and ask to exchange compromising images. He may have asked prior or will ask later to be added to your Facebook account.
Now the scam begins. He will tell you to send money via Moneygram, Western Union, Amazon gift card, Prepaid scratch off card or any other untraceable method to him.
In some situations the scammer will tell you to sign up to a cam site or they will post your pictures/video. This is also a scam. It may lead into credit card phishing.
He will tell you if you do not comply he will send the photo’s to your Facebook friends list.
Another version of this scam is Under Age girls/boys.
The scammer will meet you again on a social media site. He/she will tell you they are over the age of 18. As you progress communicating with this person/scammer he will ask to exchange indecent photographs/video.
After you exchange photo’s you will be contacted by the scammers fake "Father" or "Mother". They will tell you that you sent pictures to an under age girl/boy. They will want you to send money for therapy'damages or for them not to go to the police. In some cases the scammer has contacted victim pretending to be Law Enforcement/Private Investigators, possibly going as far as to spoof the number of a real local Law Enforcement department to make it appear that they are calling.
There are also seen cases where a scammer pretends to an online agent looking for pedophiles. This scam is using the same payment methods mentioned above. The Scammer will tell you that if you pay them they will not report it.
It is best to stop all contact with the scammers. Ignore his calls and messages.
Ignore all demands for money. If you pay the scammer he will continue to blackmail you. You will only stop paying when you go broke or realize you are being scammed.
Deactivate your Facebook account for two weeks. Change your photo or avatar when you reactivate it or get a new one. Also change your user name. Do not accept requests from anyone you have never met.
Do the above for all social media and Skype.
You may have to change your phone numbers.