I use for full disk encryption LUKS and for file encryption GPG.
Encrypting only on a file by file basis or only part of the disk is vulnerable to data leaking to swap, temp files, or other unencrypted areas. When encrypting a disk, encrypt the entire thing.
When sending files to other people, I use GPG and asymmetric cryptography. It simplifies the exchange of keys to a one time affair. Also simplifies sending files to multiple people.