I've been interested in encryption for awhile, and back in 2014 I reprinted a ProPublica article on "Protecting Your Privacy Online."
Most of the advice there is probably still not bad, but if you want to encrypt your files so that the Trump administration or just nosy people can't read them, you need to know that TrueCrypt has security flaws and has been discontinued.
A person named Sophie Hunt has written me and called my attention to an article which lists free alternatives to TrueCrypt.
A couple of other encryption notes: If you want to send secure text messages via smartphone, use Signal. (This article says it's for iPhone, but it's also available now for Android phones, too.) If you want to encrypt your email with PGP, the Mailvelope browser tool works well and is easy to use.
Another option for people who don't want to become encryption experts is to use ProtonMail, a secure webmail service which is available in a free version. Here is a review. My email address there is firstname.lastname@example.org. Here is a Wired review.
Even if you don't use encryption, enable two factor authentication for your webmail to avoid being hacked.