Have you ever been reading a story that has your attention, but the visual formatting is a little distracting? In other words, the content is great and you're into it, but you wish it wasn't so hard to look at?
Try this when you're editing/writing your own work. While you're checking for things like spelling and punctuation, make sure and check for a sense of visual comfort too. Make sure that the way it looks on the page is pleasing to you. Are the paragraphs all sitting directly on top of each other like a stack of flapjacks, or are there some spaces in between them so they can breathe? If the way it looks on the page is not pleasing to you, then it's probably not making your readers do any backflips, either.
If it's too blocky, or if your dialogue is choking under the weight of your wordy sentences... start chopping it up. Trim the fat! Split that huge paragraph into two. Let the whole thing breathe a little bit would you?!
So, keep the reader in the palm of your hand by choosing your words carefully, and by visually framing them even more carefully. Give certain important ideas a paragraph of their own if you think they deserve it!
In the end, you're the boss with the paintbrush. You'll stop that paragraph and make a new one when you're darn good and ready, of course. But keep in mind, us reader-humans are lazy and impatient, and given the opportunity we'll skip right over that awkward-looking paragraph to get to the action in a heartbeat!
It's not that hard. Give it a try and you'll notice the difference. I promise.