Make your product conform

One of the easiest ways to prevent usability issues is by making your product conform to users’ existing mental models, assuming those models are similar. For example, most users assume that the close function on a modal window will appear in the upper right-hand corner of the modal. If you place the close function elsewhere, it’s more likely to confuse (and frustrate) users.

Unless you have an excellent reason for straying from the likely mental models of your users, conforming to those models makes your product more intuitive for them to use.