Layout
Not everybody thinks about the layout of a website when they're building one, but it's impossible to build a website without a layout of some sort. Because it's unavoidable, layout should always be considered.
Negative Space
Negative space, also referred to as white space, is comprised of regions that have no content in them. Using negative space intentionally can let the reader relax, which will likely keep them on your website longer. A key component of negative space is making sure it's spread around evenly: unless there's a good reason for them not to, elements should line up in a sensible fashion.
To learn more about negative space, check out these two articles:
- Negative Space in WebPage Layouts: A Guide (Six Revisions)
- How to Actually Use Negative Space as a Design Element (1st Web Designer)
Columns
Columns are incredibly common on websites. However, they should not be used for content - users may feel confused and leave the site if they are unsure which half of a website is more important. Columns are excellent for navigation, however.