First create some cheap ideological dogma, fill it full of emotion and rhetoric. Guild it with a strong dose of extremism. Dress up in wild and frightening costumes and masks and then make a film with powerful backing music, guns and bombs.
Wear some strange unreadable messages on your forehead to imply God’s support for murder. Tell all the failures in every country in the world that the reason they have failed has nothing to do with them. It is all the fault of the government of the country they live in. Tell them to fight back in the name of God, race or freedom.
Make sure that everything in the message is emotional and religious. Avoid facts and logic, (we are talking about feelings here).
Post on social media the world over. If no one watches then execute a journalist a health worker or a captured soldier on camera. This will guarantee international media coverage and everyone will check out your post.
Then apart from keeping up with the odd atrocity - sit back and wait. Eventually the message will get out to the nutter, the sad little man whose girlfriend dumped him, the guy who got fired, the loser who knows that he is going to fail in life and desperately wants to make everyone else sorry for his failure.
This is your modern terrorist he grabs a kitchen knife, a car or pops out to the local gun shop and kills someone. No one trained him, no one prompted him directly except the media.
The loser is famous for a day or a year if he survives. Cheap, effective, durable terrorism without fear of capture.
Solution. Kill the coverage, hunt down and kill the source, alienate the countries that hold the IP address. Cut off the head of the chicken and stop giving publicity to the droppings.