Length beats complexity
Every extra character multiplies the number of possible combinations. A 16-character password of random lowercase letters is far harder to crack than an 8-character password with symbols and digits.
Current guidance is 12 characters minimum, 16 or more for anything holding money or personal data. Length is the single highest-leverage change you can make.
The passphrase method
Pick four or five unrelated words and string them together: copper-lantern-fridge-walnut. It is long, easy to type and easy to remember, and it resists dictionary attacks because the combination is unlikely to appear in any wordlist.
Add a number and a symbol if a site insists on them, but do not substitute letters for symbols (p@ssw0rd). Attackers have known that trick for twenty years.
Use a password manager
The real problem with strong passwords is that you cannot remember dozens of unique ones. A password manager solves this: one strong master password, everything else generated and filled automatically.
It also protects you from phishing, because the manager will not autofill your bank password on a lookalike domain. That alone is worth the setup time.