There are many different ways, so feel free to explore.
CreateThe tool I'm using to create my passwords is makepasswd. You can install it via Ubuntu Software Center or via terminal:
sudo apt-get install makepasswd
Then, generate random password (i.e. 20 characters):
For full list of options, use:
Its very important to create random password, with no meaning. If You decide to manualy create Your password, please avoid personal names, phone numbers etc... Use combination of uppercase and lovercase letters, special characters etc...
StoreThere are many apps which allow You to store Your passwords. I love KeePassX.
sudo apt-get install keepassx
When You start the app, it'll ask You to create master password for entering. Please, create strong password and keep it on a peace of paper and do not show it to anybody.
I'm using master password in Firefox and Thunderbird, too.
Now You can enter Your accounts and related informations in KeePassX.
KeepWhen You finished, You'll need to save it to a file. Make sure to change permissions of the file, so only You can read or write it. You can do this by
right click on the file->Properties->Permissions
and set permissions like this:
Anyway, I prefere to keep the file on USB stick key, not in my computer. Well, its up to You.