Choose a combination which is easy to remember for YOU!
The first character MUST be a letter!
Using the open source software TrueCrypt I found the following description for choosing a good password:
It is very important that you choose a good password.
You should avoid choosing one that only contains a single word that can be found in a dictionary
(or a combination of 2, 3, or 4 such words).
It should not contain any names or dates of birth.
It should not be easy to guess.
A good password is a combination of upper and lower case letters, numbers, and special characters, such as @ ^ $ * + etc.
We recommend choosing a password consisting of more than 20 characters (the longer, the better).
The maximum password length is 64 characters.
The normal length of passwords used by my own are 8 to 10 characters.
Only when I use encryption software, I follow the above advise.