First off, it is important to do research on websites in order to figure out where certain items should go. For example, the logo should always go in the top left. Why? Well because that is the first place that people look and the user needs to know what site they are looking at.
Line spacing is also very important when treating text on a website, you do not want the user to get lost while reading. White space is a good way to create balance, contrast and proportion.
Also it is very important to keep website standards in mind. An example of this would be having an underlined word on the page that is not a link-this is very frustrating to the viewer!