The Most Important Design Elements

If I was to provide advice to an online editor about the most important design elements that they could implement, here is what I would say:
First and foremost, they would have to concentrate on the attention grabbing or unique design that will serve to initially captivate the users attention and imagination. Essentially, what would you like to have your viewer see within the first three to five seconds of visiting your page.
Secondly, a web editor has to factor in the usability factor of his website. Although the initial image of a website is key to its success (especially when trying to grab one's attention), a potential user/viewer of the website must be able to navigate the site with ease, otherwise they will move on to the MILLION OF OTHER WEBSITES THAT EXISTS.
Additionally, the availability of the relevant information has to be readily available and easily accessible as well. I think that the key in keeping a user's attention (and possible return), is to avoid them getting frustrated in their search for information. Therefore, optimize what information you want to have, and decide by using an order of importance.
Listed below are a set of rules for which I found on a website (http://www.smashingmagazine.com/2008/01/31/10-principles-of-effective-web-design/) that discusses the 10 Principles of effective Web Design. They are as follow:

Don’t make users think
Don’t squander users’ patience
Manage to focus users’ attention
Strive for feature exposure
Make use of effective writing
Strive for simplicity
Don’t be afraid of the white space
Communicate effectively with a “visible language”
Conventions are our friends
Test early, test often