I've moved most of my websites over to HTTPS today using Let's Encrypt. The process took me a bit more time than I had hoped, since I encountered a segfault bug while installing the software directly from the Git repo, but after installing the Debian letsencrypt package all worked fine.
I've followed the instructions given by John Maguire, and I must say I'm really pleased to be able to ditch the self-signed certificate I had created for https://links.klein.st and provide my other sites behind HTTPS. Thanks a lot, Let's Encrypt!
Now most of my web properties get an A on SSL Labs!