There're a number of ways of keeping your passwords as safe as can be. One very old-school way is to write each password down in a book, and keep that book physically secure. On the assumption that you can't remember the passwords without the book, this is a reasonable way to improve your security. Sadly it doesn't scale well and can make it quite hard to keep things up-to-date.

More usefully, in today's multi-computer and multi-device world, there are programs called 'password managers' and as with anything even vaguely interesting there are a number of them to choose from. Some names you may already be familiar with include Keepassx, 1Password, and LastPass.

Password managers offer you a way to effectively protect all your passwords with a single token, often allowing you to sync and manage your passwords without needing lots of knowledge of how things work. They're usually also integrated with your web browser, your phone, etc, to allow you a seamless experience.

If you're a little more paranoid than the normal geek though, and you're prepared to sacrifice a bit of simplicity for a bit more ease-of-mind, then you could try Password Store (pass) which is written in Bash and uses GnuPG. I personally use pass and have my GnuPG key stored in a Yubikey which I keep around my neck. (There's also the Gnuk which can, I believe, do a similar job) With the need of the physical token and also the PIN to unlock it, this is a multifactor authentication system which I then can use to secure my passwords etc. I then have it backed onto my own Git server where I can keep an eye on the content safely.

I strongly suggest that if you're not using a password safe of some kind, that you get one set up and start using it. In fact, if you've not got one, go and do it now and I'll see you next time...

(Oh yeah, and if you look at multifactor authentication, be aware that your intrinsic factor today is simply your adversary's posession factor tomorrow)