what is the easiest way to protect an idea? are there any international organisations that protect ideas for free?

Keeping it to yourself.

Really though, even if you have a patent or a bunch of lawyers, other countries don't have to abide by those laws. If anyone figures out how to do or make whatever it is you needed the patent for, they can do it. I feel that's the way it should be. No matter how great the idea, keeping a patent on it restricts other people from taking the idea and improving it.