I have several email accounts for different purposes so they all need their own password. Then if I do online banking, shopping, social networking etc that's even more passwords not to mention account usernames and memorable information!!
Well I don't know about you but I just cannot keep all that information in my head and I KNOW we're not supposed to but I have to write it all down. Not on scruffy bits of paper to get lost, but a notepad file (saved on some kind of external storage) or an actual notebook (make sure you don't lose either). I have to write them logically, grouped for household items, banking, shopping etc:
~ Web address
~ Username
~ Password
~ Email address used to create the account
~ Any other information required
That way I can see at a glance when my memory fails me!
Remember not to use the same password for something as what the email account uses; and if using the same email for different accounts then again each account needs separate passwords!! Also I NEVER check the box for 'remember me' or 'save password' etc especially if I am on a computer other than my own.
And the worst thing?? We're ideally supposed to change our passwords on a monthly basis... Oh dear it makes me feel stressed just thinking about that.
If you are the sort of person who has trouble thinking of a good password, there are lots of online password generators with lots of handy tips and dos and don'ts for creating strong passwords.
So many times when I'm doing some computer tuition or just helping someone out with something, an account for shopping online or email etc has already been set up either by themselves or a third party BUT "quel horreur" they've forgotten either the username or the password and they look to me for the answer - as though I can just pluck it out of the air, just like that (if only). Ok well yes often there are ways around it but it all takes time and can be a bit of a faff.
So in my opinion.. WRITE IT DOWN!! (and keep your stuff safe ie. preferably not next to your computer).