I simply use the same password everywhere. In cases there that's not possible I have a password protected spreadsheet that I use to capture them.
One rule I follow is to also use a combination of letters and special characters + a number to make a word I can easily remember. For Example:
G0R3D$04 = Go Reds with a zero for the letter "O", a 3 for the letter "e" and (obviously) a dollar sign for "S".