what i've been doing for years is this:
i think up a phrase like: "No body will ever break that pass word but me".

then when i have to write the password, i only write the first letter of each word; this is the result:
if a site also wants at least one number in the password, then i just add the number 1 at the end.

no one can ever guess at the phrase i use, much less at the pass itself, and this combination of letters can't be found anywhere.

works good for me.