You can also write passwords down if you really feel the need to do so, but make sure if you are, that you take more precautions if you're someone who may be targeted in real-life.
For example, the password "_4?3!JrEWbV6T99rZ7+96S2S@&$_qP". You can split it up into several groups scattered on the paper at different places, not in order, and all you have to do is remember the order of the groups when typing it out online.
Another technique is reverse-typing passwords, which makes the group splitting up when noting it down even more secure. Therefore, say you were making a group of characters belonging to the password for the example mentioned above, and those characters were "_4?3!Jr". What you could do is note down "rJ!3?4_" instead. For other groups of characters for the same password, you could not use reverse order.
Even if someone gets that piece of paper... they do not know the order of the character groups to form the original password, and even if they do, they aren't going to easily get the real password if you've used deceiving techniques like reverse-order.
If you want to step the game up even more, you can add things like groups of characters from the password in hash checksum form, or go straight to level 1000 and invent your own alphabet to manually translate characters to a different version (e.g. "A" becomes "b", "b" becomes "C", "c" becomes "z", etc.).
Make them use multi-lingual characters or translate foreign language words for fun and to waste their time.
As for security questions, you can put fake answers. If they happen to know the real ones... well, bad luck to them, it won't work in this case. I like this technique a lot. The answers could be something only you would ever know, despite being related to the question at all or not. Or, the answers could be strong mini-passwords (e.g. certain character length, using combination of both upper-case and lower-case, containing numbers and special characters, not being anything personal related, etc.).
Obviously, all of this will be time-consuming and not applicable for most people, and only really necessary in certain situations. For 99.9% people, all you will need is a normal password manager, but I just thought to note these tricks for anyone who is paranoid and/or interested in it for entertainment purposes.