This covers everything from font choice, line breaks, paragraph sizes, even interfacing with more inline story elements such as the opening sentence. Books are judged by their covers, and so they should be. Presentation matters, and everything is important.
I bang on about this a lot, mostly because I like to worldbuild (Amazon Lumberyard gets me incredibly excited, as does inkarnate.com). But my point is that I see alot of writing that is quite talking-heady. There's dialogue. Lots of dialogue. People are really talking here. But where are they? What environment are we in? Why do we care?
I understand that fiction is in many regards about people, but remember that everything, particularly in fiction, is connected, and if it isn't, it should be. People exist alongside their environment, not apart from it. Yes, even the most die-hard climate change denier will be situated somewhere, so make that somewhere indicative of something about them. I call alot of this scenery props. It doesn't have to be a sweeping majestic vista of mountains and rivers. It can be a thing, an object held in hand. What does that object say about the person and the place they are. You are God. You don't have to play by any rules. If you want your antagonist to be wielding a blunderbuss in your space opera setting, then by jiminy give them one. It fleshes them out, makes them more real by giving them a quirk and a personality that readers can like and invest their emotions in. What's more: you can manage the mood via that blunderbuss. Trust me, I am aware how this sounds, but if you want, for example, a slow moment building up to tension, then let the blunderbuss be the vehicle for that. Have your villain wrap a delicate grip round the polished, reflective knotwood of the stock, caressing the time-battered barrels with a loving finger. And look, right there, I have made the hand and the finger as well as the gun props too. You are allowed to imbue these inanimates with both telling physical features and some sort of anthropomorphic nonsense because they are being perceived and experienced, and loving and battered are emotive words for things felt by an observer. Knotwood may be a cultural or regional touchstone that comes with its own baggage. Dropping a little alliteration and sing-songy assonance in there (battered barrel, polished knotwood stock) helps ease the image home. Devices, devices. Use 'em, use 'em. Anyway, this brings us onto...
As I said earlier, I love worldbuilding. I love it so much that my earlier writings were whopping great infothumps about scenery and people, frequently going about their workaday business, but mostly not even that. Mostly everything was just being, near everything else. I had it pointed out to me that stuff needed to happen. But, I spluttered by way of reply, what of my glorious expositing? Surely you don't mean to say that I should eviscerate my beautiful settings just to, p'too-ey, make "stuff" "happen". How dreadfully gauche. How anemic.
Fortunately there is a way of combining the two. What I learned was, rather than having things be presented statically, present them dynamically. 't the hell do I mean? Example.
The cat sat on the mat. As it looked at me, it told me to get lost.
The first sentence here is kind of narratively redundant. It basically says: The cat sitting on the doormat was busy being a cat sitting on a doormat. The second is just blah. But below, I rolled out some fun verbs like swung and hissed and lazed to make it more sensory and active and doing of the precious stuff. I describe the doormat and the cat and its eyes and so on via synecdoche - calling a thing by some notable subpart, like referring to your car as your "wheels". I abuse and torture semantics, and in so doing, invent a thing - is "scratches" a noun? It is now.
Lazed out on the threadbare scratches of manila hemp underneath the porch threshold, the large calico - a Tom, by the size - swung its lambent greens my way. "**** the ****ing **** off my ****ing doormat," it hissed.
But most importantly I make the operating verb something other than the literally sedentary "sat". The cat lazes on threadbare manila, exercising doiminion over it, and swings its glare - towards YOU. Like the finest reuptake inhibitors, that verb choice alone helps me with my mood. And yes, I cruised the Wikipedia page of the history of doormats for even this little bit. At this point you should be thinking about similes and metaphors and imagery too to move it along. Living things looking at other living things is - well, it's not even a trope of literature, it ... I dunno, it just has to happen at some point. There's no getting around it. But "looking" is such a tedious word, so why do that when you can swing your lambent greens instead? That way we invoke a large and powerful feline without once mentioning the word "cat". Obviously there's a limit and things must be appropriate to the subject (cat, mat) and the mood (power, threat), and importance; if this is a minor event, we may not want to go all out; save our best plays for the right moment sort of thing. This way, we have ended up with even more worldy-buildy than before, but with actual motion happening along side the stuff being. All these adjectives and verbs and synecdoches are specially selected to create a mood. They could probably be substitued one for one to make another mood, but the spots for them ought to be there as a start.
Mixing It Up And Keeping The Flow
All this being said, I think it is important to keep things fresh. If you stick rigidly to one thing, there's that point where it clicks over a terminator line and goes from being cool to being annoying, I have oodles of first hand experience at that. Now, it is okay to cross that line, if for no other reason than to know or suspect you have crossed it and can edit your way back (unless you have a clear reason for not doing so, usually for some sort of comedic effect or "meta" weirdness), but if the endgame is controlled authorship, don't overegg it. Just dropped the world's best-ever sentence that invokes a ton of whizz-bang stuff, moves it about vividly, and dazzles the reader? Great. Then chuck in an "it was" clunker very next clause. Because you can. Because you have that control. Because - steady now - you know what you're doing. Because - and click - being dazzled! By everything! All the time! Will get very boring! No matter how totally amazing! And no-one wants that. Let your text ebb and flow to the natural rhythms that pertain to and communicate its mood.
Want a fast and choppy, urgent mood? You could do worse than short, staccato sentences. Sudden things happening. Engage the senses - bing, bang, bash. Or perhaps you want a more pastoral evocation? Stretch the clauses out, drape them over the reader's senses like exotic plantlife threaded with strange and gorgeous floridity, buds that stir the humours, pollen drifters on currents of air. Do both. Don't hold yourself back to what can be seen or what is factually present. Someone here mentioned that they stand about in an empty room and imagine their story is an immersive VR experience and I think that is a very good way to do it because really, that is our goal. The human brain is capable of perceiving all sorts of stuff. How it is all input is almost immaterial. Most people experience extremely vivid events with no external input on a daily basis. They just happen to be asleep and dreaming while they do it. So if the brain can concoct all that HD colour business with no immediate stimulus, imagine what it can do with a few words. Words are useful and beautiful, a sort of notional lego from which all things spring. Imagine what it can do with the way those words are written. So use style as a tool.
Maybe others have some thoughts too. I'm on the lookout for a kind of dictionary for this sort of thing; eg. when, in literature, you encounter, say, a dog, or a dark cloud, or a grand house, what does it mean? What must these things be doing, to gee up which emotional reaction? Or what could you put there to create a particlar feeling? Maybe this is a bad idea and it should all stay in the ephemeral realms of artistry. I dunno. What say you?
And no, I too cannot believe that I wrote "notional lego" and "mood management blunderbuss" Oh well. Here goes. Submit.