Most systems require the following:
Be at least 8 characters in length.
Contain at least 1 lowercase and 1 uppercase letter.
Contain at least 1 special character (!@#$%^&*)
Contain at least 1 number (0–9)
My scheme satisfies the above and is unique to each site and easy to remember.
Something related to the site
A special character
My first name (capitalized) or some word
The year (either current or a constant difference from current)
So, for my fictitious HSBC password:
HSBC$Nathan2021 (current year + 4)
For my fictitious Vodaphone account:
Voda$Nathan2021
The parts can be in any order the password system will accept but should be consistent across sites.