It all depends on who you are trying to secure against. For example, everyone says not to use things that are important to you because they are easy to guess. The thing is, if you are worried about outside hackers with no connection to you, they have no basis of guessing that stuff. In most attacks, the hacker has no clue who the account belongs to, so they have no idea that Pepper is your dog and 11/23/99 is your wedding day, so Pepper!112399 is not a terrible password. On the other hand, if you are worried about targeted hackers (whether it is someone who takes the time to actually research the user or someone in the user's life), that is going to be an easy password since they will know that information.
If you are worried about outside hackers, one of the best thing you can do is make really secure passwords and then write them down and keep them in your wallet. For most people, your wallet is one of the most secure places you have, since you already keep cash and credit cards there. Yes, people in your house have access to it, but if those aren't the people you are worried about it works great.