I have a tip to have a memorable password that is different for every website.
Think of a line from a favourite song or film. For example, 'I'm dreaming of a white Christmas' Something longer is better, but this illustrates the point.
Take the first letter of each word, so idoawc. To make it more secure, change the letter i to the number 1 or an exclamation mark, the o to the number 0, the a to the symbol @. You then have 1d0@wc or !do@wc. To complete it and make it different for each website, end it (or start it) with something that relates to the site; the obvious being wc for here, mh for motorhomer, MS for Marks and Spencer etc.
Voila. A memorable, different and unguessable password for every site.