Which element within a composition immediately grabs your attention? The dominant element on a page dictates the alignment and tone for all of the other elements and, of course, stands out the most. 

For example, a landing page may include a lot of elements — headline, subhead, image, signup button, etc. — but the headline is the first thing that stands out to users. Set your dominant element apart from the rest of the page via scale, color, and placement.