Don't reinvent the wheel
It's also called Jakob's Law. Yes, the same Jakob Nielsen I was mentioning above in Laws of UX. People spend most of their time on other people's sites (and not yours, sorry). That means that they expect your site to work in the same way these other sites operate, so they can use it easily. A little bit like driving abroad. It can be different, but not too much (so not like wild countries who drive on the left side of the road, no).