According to the traditional advice — which is still good — a strong password:
Just bash your fingers against your keyboard and you can come up with a strong password like 3o(t&gSp&3hZ4#t9.
That’s actually a pretty good password — it has 16 characters, includes a mix of many different types of characters and is hard to guess because it’s a series of random characters.
But it's also nigh on impossible to remember.
Assuming you don’t have a photographic memory, you’d have to spend time to drill those characters into your brain.
There are random password generators that can come up with this type of password for you but they’re generally most useful as part of a password manager that will also remember them for you.
So, how can you create a memorable password that's not something obvious?
One trick is to come up with a sentence or a couple of sentences like The first house I ever lived in was 613 Fake Street. The rent was $400 per month.
Now, turn that group of sentences into a password by using the first letter of each word, so your password might then become TfhIeliw613FS.Trw$4pm which is actually quite a strong password of 21 digits. Sure, a true random password might include a few more numbers and symbols and upper-case letters scrambled around, but it’s not bad at all. You just need to remember two simple sentences, so it’s easy to remember.
Perhaps also consider: