Protection from insiders

Can I protect myself from an insider?
How to avoid information leaks?
Is not the scale of the problem exaggerated?
What methods of protection are really effective?

First a couple of words about how it works.
All people working in your office have access to information on your computers and it's easy to copy:

• drop by e-mail,
• Chat or forum,
• copy to USB flash drive, CD, DVD, ZIP, Floppy,
• through wireless networks (Wi-Fi, Bluetooth, IrDA) ...

And if this is not your office, but the office of Yandex, Mail.ru or Google. And there your information.

There should be a system of control, selection of employees, prestige of work.

What can we change here?

The answer is simple - nothing, we do not even know them. But we can influence. For example, I do not really trust Mail.ru in the light of complaints about them on the Internet. Perhaps this is not so, but God cares. I prefer Google, because it's a Western service, and their honest name is very expensive.
That is, we choose those who can offer better reliability.

Another weapon, if we have problems with information leakage, we must assert our rights. A decent Internet service will defend its good name and you just need to be persistent.