Computers are pretty damn good for a lot of things, but they can also be a bit of a liability.
One of the best ways you can protect your data online is make sure your password is hard to crack, in case someone gets their hands on your password hash. If they get it in plaintext, good bloody luck.
The longer and more complex your password (and therefore a password hash) is, the longer it takes to crack.
And despite some of the suggestions on here, it's best not to use words themselves, because they can be easily loaded from a dictionary by whatever brute-force program is being used. Best practice is to use a sentence (for ease of rememberence), but only type in the first two letters of each word, for instance.
Or, if you'd prefer to fang the responsibility off to someone else, use a password manager.
Here are some resources, if you don't believe me: