I've started to make up answers that could be accurate, but aren't obvious / the first thing someone would guess. For example, if the question is "where were you born?", I pick a random city.

I have read a suggestion that one should pick real (but randomly generated) words because, where it is possible to call the company that maintains your account, an attacker might claim that the recovery answer is a series of random characters, and there is a chance that the employee will accept this and allow the attacker access to the account.