Pretend like you’re a human being
With the possible exception of artists and architects, no one is more full of shit than designers. We can find a way to justify anything. Blah blah blah. That means no matter what you end up with, you can come up with some reason why it’s a good design. The best advice I have for designers is to practice being not-designers: stop what you’re doing, close your eyes, take a few deep breaths and then look again like you’re just a regular person encountering this product/service/user interface/object/page/poster for the first time. Where do your eyes go? What do you think it is at first? How do you figure out what you are supposed to do?