There are very few passwords you should have to memorize.  The only passwords I have memorized are my personal Apple ID, my Bronco NetID, my personal Gmail account, my Dashlane master password, and the password to a shared work KeePass file. For those passwords you must memorize:

Use four or more random words or a phrase.

• https://randomwordgenerator.com

Take inspiration from poetry, books, or movies:

• HomeWizardRubySlippers (The Wizard of Oz)
• TartsTreacleCheshireCat (Alice in Wonderland)
• VogonFishTowelBricks (The Hitchhiker's Guide to the Galaxy)

Have I Been Pwned lets you enter an email address and see if that address has been compromised in a data breach. If it has, you will be prompted to update your passwords for the relevant website. 

https://haveibeenpwned.com/ 

Every other password I use is stored in a password manager.  I use Dashlane for all of my personal accounts and I share a KeePass file with two members of my department for shared work accounts.

Why you should use a password manager

• KeePass
• Dashlane
• LastPass
• 1Password

Using a password manager allows you to have incredibly strong passwords that are:

• Random (yes, you read that right: completely random)
• Incredibly long (32 characters works in most applications; why not try 64 characters?)
• Unique to every site or service

Create random, unique passwords by using a random password generator:

• http://passwordsgenerator.net

I use the following settings when creating random passwords:

• 32 characters (or more)
• Include Numbers
• Include Lowercase Letters
• Include Uppercase Letters
• Exclude Similar Characters
• Exclude Ambiguous Characters