It helps me remember my password if I pick passwords that have some relationship, maybe things I see out my window or things in a certain room at home. Just don't pick obvious words like children's names or your name spelled backward. It's not a major sin to write your password down if you have trouble remembering it. Just don't write it down where others can find it. Keep it with the same care you keep your credit cards.
Hackers know all the tricks to guessing passwords.
It is pretty easy to get a copy of the encrypted password file from most UNIX systems. There are readily available programs which run on RISC workstations to crack these encrypted password files. There are other programs which will automatically try every word in the dictionary as a password. Here are a few ways to pick a password that is hard to guess or crack. Combine words or letters and numbers.