From my experience so far, it seems like almost everyone reuses a few of the same passwords to log in to everything they use across the internet. And that's a bad idea. If any website you use is compromised, it is very likely that your login information will be tried again on another site. Not to mention if LulzSec happens to find your password, they will likely publish it.The solution is to use a password manager like LastPass or 1Password. They're both fantastic. I use 1Password as it is optimized for the Mac experience (although now it is also available on Windows), but it sounds like LastPass has become just as polished (not to mention that it's free).
A password manager is a program that allow you to securely save all your passwords using one master password. While having a master password may seem like it defeats the purpose of having multiple passwords, think about the alternative. If your Facebook account gets hacked and you have one password for all your logins, you will have to change your password for everything. If you have a long password as your master password and hopefully change it occasionally, it is highly unlikely to be cracked with "brute force" where a computer randomly generates words and letters until it cracks the code.
Password managers can sync across browsers and computers so no matter where you're trying to log in to a site, your passwords will all be handy. They also have extensions that make password managers really quick to access from your toolbar and autofill your login information.
It's really worth the little bit of extra time it takes to set it up... rather than a full tutorial, just let me know if you want any help with this.