Do you know how long is enough? Of course 64 chars would be dope but I'm not good at memorizing things. I know it's trainable but I'm lazy too :)
My current password is a bit longer than 10 chars and I wonder if I should upgrade it.
Personally I started doing this ~2000. I still remember my first one that I gave up meanwhile because I told it to my GF at the time and we broke up meanwhile.
You can easily top 100 characters this way. Though this is not something you want to do on a touchscreen device, it's a pain there with fat fingers.
A 10-word diceware passphrase is often recommended.
If you choose a password rather than a passphrase, the bare minimum is 15 (90 bits) to 22 (128 bits) characters, upper and lower case and numbers.
Either way, purely random is key here.