Where it gets tricky is that as programmers we are also power users and our mental model of what we expect to happen and what a user expects to happen diverge, I try to have empathy for the user.

One of my tricks is to imagine what my mum would expect to happen (not because she's a woman, it's not a sexism thing I hasten to add) but because she's a 60yo woman who didn't start using a computer until she was in her 40's and is slightly wary of them still.

If it passes the mum test then I know I'm on the right track.