Bad passwords can be cracked easily when using computers. Plenty of recommendations exist for secure passwords. Some of these are:
A password should not contain public or personal information like the name of your pet, date of birth, or username.
A password should be long.
A password should not be an existing word or a combination of few words. It should be a combination of characters or words that is as random as possible.
For each purpose, a unique password without similarities to other passwords should be used.
If you fulfill these requirements, you quickly reach a point where remembering the passwords gets impossible. Thus, we recommend to use a password manager to generate and store the passwords. By doing so, you only have to remember a few or a single secure password. Otherwise, we recommend to use at least 10 characters, ideally use sentences instead of words.