Making your write-ups easier to read
In page layout terms, white space is used to make a document more readable, by giving space for the eyes to rest. In designing documents, for example, wider margins are often used to direct the reader's eyes to the centre of a page.
Generally, the denser the words and paragraphs, the more tiring it is to read. You may witness this for yourself - write-ups with long paragraphs make for more difficult reading, and the longer they are, the more difficult it becomes. On E2, you should try to use the <p> tag to open paragraphs rather than the <br> (linebreak) tag - or even by simply hitting the Enter key twice when creating your draft.
The <blockquote></blockquote> tags can be used to create horizontal space, to separate out part of an article from the main body. They can also be used to truncate the <hr> horizontal rule, as demonstrated here, although <hr width=150> (or similar number) will do the same, thusly:
In addition, using subheadings relieves the eye of the reader. My personal preference is for a <strong>
tag, which does two things; it creates a resting place for the eye, and breaks up a solid body of text, and also alerts the reader that there is another section, with its own 'theme'.
Not that it applies in E2, but in paper documents, the gutter between columns is also a kind of white space.
By checking your write-ups in your drafts and experimenting with white space, you will render your writing more accessible to your reader. Make it easier to read, and it stands to reason that it is more likely to be read as s/he will feel happier about it.
Thanks to heyoka for her input, and gnarl for his!