In this article, I will explain why trust is good, but encryption is better

You can't trust intelligence services

After Edward Snowden, everybody should know that intelligence services like the NSA are watching, even if they say they're not.

Basics

Encrypting data isn't that simple. To securely encrypt data, a secure algorithm and a secure private key have to be used, and many other aspects. Most algorithms used today can be easily decrypted by the NSA within hours. For example, the RSA 4096-bit algorithm was cracked by using a microphone, which listened to a CPU encrypting a file.

On the other hand, algorithms like PGP haven't been cracked by the NSA, yet.

Private keys

Probably the best way to get a good private key is to randomly string characters together. But the random factor has to occur offline, for example throwing dice.

But the best way isn't always the most convenient way, as a random string of characters can't be remembered as good as a birthday, or any other event in your life. But these aren't secure, as they could be easily found out with social engineering.

So the best way is to remember an event in your life, and for example just take the first character, and encrypt these characters with your own rules, for example, "I" becomes "1".

Algorithms

There are many algorithms to chose from, AES, PGP, RSA and many others. But how do you choose the perfect algorithm?

For me, a perfect algorithm has to be fast to decrypt with the right key but slow for the wrong key, so brute-forcing through the encryption isn't an option. It also has to be non-human, or machine readable, so a simple caesar algorithm doesn't do the job. I chose AES-256 over any algorithms for offline data storage, as it fulfills most of my demands. My whole hard drive is encrypted with AES-256 and other important files I don't use daily are encrypted with RSA-8192, as this is more secure, but takes ages to decrypt.

TL;DR

Encrypting files properly is hard, as the intelligence services won't just tell you which algorithms are secure. Also, it's hard because you have to have a strong private key and, a strong algorithm, and a fast processor to handle the decryption.

As always, do your own research. This just serves as a little insight and will hopefully get you going.