Detail. Detail everything!
Detail is what separates good writing from bad. Most of the time, we go with the “there is no right or wrong way” mentality, but this is one area where that’s not true. Detail is simply better than no detail.
Detail is the difference between: “He picked the pencil up.” and “He leaned down, extending his arm, his fingertips brushing the rough, plastic surface of the table as his hand closed around the dented, chewed on pencil.” Now which one of those was more interesting to read? Which one told you more about the setting?
What kind of detail is, of course, where it gets interesting. Regardless of what you are writing, you do need lots of detail, but on what aspects? If you obsessively describe every single move of your character from rubbing the sleep out of his eyes to how he brushes his teeth, your book is probably going to be boring. But if he has some special little flourish when he walks, a specific way he turns on lights; that’s something to describe in detail once, to help get your reader more involved.
It’s not specific to genre so much as scene-focus. In general, a hard-sci-fi is going to have a lot of detail in the mechanics, physics, and design of the technology(or techno-babble). Fantasy is going to cover setting a lot more thoroughly; majestic castles, enchanted forests, whatever.
Heavily character-centric portions need much more detail on emotions and actions. Looking at yesterday’s example, the section goes into a lot of focus on Aden’s feelings after he kills another. This is the sort of thing that helps realize him for the reader: he’s not an unfeeling killing machine, yet he believes his actions were so justified that his only regret was enjoying the act, reveling in his revenge.
Detail is also useful in building suspense. If done right, describing every heartbeat leading up to some major battle can have the reader’s heart pounding right along with the hero. One of my favorite examples comes from the Sword of Truth series by Terry Goodkind. In the first volume, the author takes about two and a half pages to describe how the protagonist jumps off a small rise and hits a guy with his sword. But he puts so much detail into it that my palms were literally sweating as my eyes took in each word, it was just that well composed.
But sometimes, a lack of detail can accomplish the same objective. In the section leading up to the little preview of The Next Progression that I offered yesterday, we only see the moments leading up to Aden and Diego’s fight, then the aftermath. It adds an air of mystery, but at the same time allows the reader’s own imagination to fill in the gaps.