If you are remembering passwords at all, then you are probably making a mistake. Easy to to remember, generally means easier to hack. That doesn't mean you will be hacked, but that won't be for having good security, it will just be luck, and luck is a poor security strategy.
A good password strategy should include having strong passwords, having different passwords for all sites, and changing them frequently. Strong passwords should include lower case letters, upper case letters, symbols, and numbers, be long, and not include recognizable words or number sequences.
For most people, memory isn't going to be good enough to implement such a strategy. My recommendation is a good password manager. With a password manager, you can generate long random passwords, and have the password manager log-on to sites for you. It can also remind you to change passwords regularly and some will test your passwords to see how strong they are. All you have to remember is one master password to get into the manager.
People also shouldn't be so flippant about 'unimportant' sites such as Facebook or other social media. Many people do not realize how much information can be found out about a person from something like Facebook. Even with out hacking into it, you can often find out people's friends and family members, sometimes where they live, in general, or even specifically. If a hacker gained access to someone's Facebook, then they can get emails and possibly phone numbers or addresses, and that information would grant a would-be hacker the ability to do some further damage.
All passwords should be strong. One weak password is like having a super security system on your house but always leaving the backdoor open.
At the very least, everyone should include a number, symbol, uppercase letter sequence in their passwords. Even if it is the same sequence, it will make simple brute force techniques much less likely to succeed. So for example if you are using "moondust" as your password, convert it to "moon4$Dust" and the time to hack it goes from 2 minutes to 4 hours. You can check password hack times here (but don't check an actual password, check one with a similar pattern): http://blog.kaspersky.com/password-check/
Comparatively, a random 10 character sequence which includes numbers, lower-case and upper-case letters, and symbols will take 68 years.