Use of password generators and password management tools is fine, and some people have the discipline to use them.
But let's suppose you are not one of those people.
Here's a simple method to build a strong password:
Create a sentence that is meaningful to you personally, but not easy for anyone else to guess.
for example:
"Sarah and Bill moved to Chicago in 1997 with their children Sally and William Jr."
Use the first letter of each word and all or part of the numbers
SaBmtCi97wtcSaWJ
Add "characters" !@#$%^&*()+=" to strengthen your password.
Avoid repeating characters and sequenced numbers AAA abc 1234 2222.
Avoid using patterned keys from your keyboard.
cft6vgy7bhu8nji9 <-- looks "random" but type it out and you will see that it is a repetitive diagonal pattern.
Avoid using your login name
Don't try to be clever: "password" is the most common password used, followed by "secret", followed by the person's name or birthday.
Don't store your passwords online or in a document file labeled "secret passwords".
Don't use the same password for all of your login accounts.
Don't reveal your passwords to other people.
Change your passwords regularly.
Never type your password into a computer that you don't totally control.
-- at a friend's house or internet cafe, be prepared with temporary passwords to throw-away accounts.
If anyone has physical access to your computer and is able to log into Windows, your passwords can be compromised.
Therefore, password-protect all of your login user-accounts and your Network Router.
If you have been infected by malware, have a competent expert examine your machine's system to clean it up.
--change your passwords after cleaning.
The best place to keep a record of your passwords is on a secured piece of paper.
Use Microsoft's Password Checker to test the strength of the password you create.