The printed page and the computer screen are visual media. To engage the reader, you need to do more than spell everything right and make some sort of sense. You also need to make your writing look inviting.
At a high level, that’s traditionally the job of a page designer: deciding which typeface to use, how big it will be, how far apart the lines will be spaced (that’s called leading), how wide the block of type should be, and whether there will be any art elements.
At the most basic level, however, you have control over a few things. With software such as Microsoft Word, you have control over a lot more than you would have in the days of the typewriter.
One of the most important aspects is how you break up your text into paragraphs. A huge block of text will chase away all but the most dedicated reader. A paragraph break gives us a chance to take a breath before we move on. The reader sees manageable chunks of type instead of a solid wall.
Making a separate paragraph out of each sentence is almost as bad, because it’s unlikely that you are really launching into a new thought with each sentence.
Then there’s the matter of emphasizing certain words. You can use bold face, italics or underlining, but go easy with them. Most of the time you should be able to convey what’s important without typographical tricks. And try to limit yourself to one tool at a time. If you also start using italics, underlining and other tools together, you risk making the page look like a circus poster.
If you do have control over the typeface, pick on of the usual suspects such as Times New Roman, Helvetica or similar faces. If you put everything into fonts such as Mistral, Comic Sans or Old English, you are only making your reader’s job harder.
Single-spaced type is readable, but it can make a reader feel claustrophobic. Give it a little air. A space and a half usually looks good.
When you start paying attention to this stuff, you start to appreciate what a good designer can do to make reading pleasurable. It’s a lot like a restaurant. The food is the most important element, but good presentation can turn a meal into a great night out.