Warning: Your cat is probably going to guess your password.
Don't use your cat's name, birthdate, or any other easily guessable info.
Use a mix of letters, numbers, and symbols (but not just a mix of letters and numbers, that's boring).
Make it longer, like, at least 12 characters.
Change it often, like, every 30 days or so.
Use a password manager, like, the one that's secretly controlling your mind.
Advanced Password Security Tips for the truly paranoid.
Password Security Tips for Memes (just kidding, don't click that).