This is an important security item in every case. Short, simple passwords are so easy to guess or crack that the protection is practically just as bad as having no password at all. It may help to think of it as a pass phrase, and construct them of several words. Next, use combinations of upper and lower case letters, and use numbers mixed in as well. It's not as hard to create something that would be hard to crack but easy to remember as it might seem. Length is the most important factor, followed by mixed case and the addition of numbers and other characters if they are allowed. Try mixing several words together and numbers within, using things that are easy for you to remember.
For example, for a really complex password you could combine your favorite flavor alternating with a movie name and bracketed by the year you graduated high school:
Chocolate, 1986, Star Wars = 19CShtoacroWlaartse86
OK so that's going to be tough to remember at first, but no one is likely to crack it.