http://coinmamailtcrg7fw6uorut3d35bk35rtmntkrtb4fgeov6pefvfutqd.onion/blog/how-to-choose-a-strong-password
Use a password manager such as LastPass to generate secure passwords for the sites you visit. Even more importantly, choose a secure password for the password manager (see above), one that you won’t forget and that you don’t use on any other sites.