I recently saw the comparison that sending unencrypted e-mails is like sending letters without an envelope. And so I was finally convinced to try it, after hearing about it for years but considering it too much trouble for a little extra security.
It turns out that after installing and configuring the system (which wasn’t that much of a hassle), I barely notice a difference, except that I can feel safe that I and the recipient are the only ones reading the e-mails. I use the Enigmail add-on on Thunderbird on Ubuntu, but there appears to be lots of different variations depending on your needs. I used this Enigmail quick-start guide, but I also found this one which appears slightly more user-friendly. If you’re using Gmail on Firefox, check out this extension.