Alternative mnemonic method
Alternative mnemonic method: generate random letters, then make up the mnemonic to suit the letters, You'll have to write the password down in the first place - and maybe the mnemonic - but after a few repetitions it will stick.
I have to use systems that impose rules, and while I could maybe break those, instead I use this method:
Every password in the same format.
The format is 2x letters and 2 numbers, and the letters and numbers are random - not repeated - and the letters are consonants. The first letter is capitalled. This meet various system requirements of:
Contains letters and numbers
Contains upper and lower
Does not contain any English word
Repeated letters are quite a stupid rule although I suppose you want to block "passssssword" as a password (but, why, Register wants long passwords, that is long)
The password is constructed by taking random source and skipping any input that doesn't fit. If the source is letters, then A to J represents 1 to 0 (after 9) and K to T likewise.
The middle letters of words from a book yield: Hvnk5ypsb4
But pure random text is more consonanty.
Then convert the letters to a sentence like "Havink your pure sweet Bovril". Never mind the numbers - if the mnemonic brings back the password letters from memory, then, for me at least, the numbers come too.
Add ! at the end for a system that rejects a password without a non-alphanumeric symbol. B!@#$£rds.