Conventional wisdom recommends using a unique, randomized, long password for each set of credentials you setup for your use. It increases security and prevents loss of multiple accounts if any one account gets hacked thereby leaking your creds.
Conventional wisdom fails to say anything about remembering these unique long hieroglyphs. How very convinient for conventional wisdom.
The solution to this problem, like every other problem is to make it someone else's problem. In this scenario, a password manager's.
A password manager is a software that does the job of generating such unique randomized passwords for you, storing them and giving them to you when you need them, like an obedient lackey. In return all you have to do is to remember the one password for the Password Manager.