You can take it with you: How to destroy the data you leave behind.

Because of how Apple throttles and controls password input to deter cracking, its password doesn't have to be nearly as long as ones stored elsewhere in which a password cracker could obtain the encrypted form of the password and perform trillions of offline brute-force tests. But also… Password manager password: Except for iCloud Keychain, set a strong password that you memorize and otherwise make unavailable to other parties. Strong passwords: To prevent people from guessing your passwords, make sure that at all services at which you store private data or leave a record of what you do, you have what's currently considered a strong password. [Extracted from the article]