A sensible way I've been recommended but don't use myself is to have your basic password, say "spongefingus" and then decorate it as required with something that hints to the system you're using, if you can keeping the number/pattern of numeric, 1337 is easy to remember, and non-alpha numerics the same.
So if your password changes monthly for your work PC it could be
[July-W0rk-Sp0ng3fingu5]
or your email:
[3m4i1-Sp0ng3fingu5]