This is an old revision of the document!
A rule of thumb in security is proportionality: more sensitive, more important files get stronger protection. The more protection you put in, the more cumbersome it is to share and use such protected files or data. So it's going to be a balance between security and usability.
* KeepPassX
Use this app to manage your passwords and other important info bits. In addition to using a strong password (at least 8 characters, with certain characters in capital, also using both numbers and special characters), it is recommended that the database and passkey be placed in separate locations.
Save any changes you do by clicking on the Save icon.
* TrueCrypt
For users on Mac OS v10.12.6 (or possibly later), download this tweaked version. With Truecrpyt, create an encrypted container, mount it, put in important files, and dismount it. Note: the containair size should always be slightly bigger than the total size of files to be put it.
Drag the file that needs to be secured to the mounted container file.
xcode-select --install
/usr/bin/ruby -e "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/master/install)"
Then install osxfuse and sshfs
brew cask install osxfuse
brew install sshfs
Alternately, this version of osxfuse. It may need a reboot.
* Tails - stand-alone operating system. See installation assistant
Use this app so as not to leave more digital footprints on the computer you use and elsewhere. Downside: slower apps running.