Sometimes you can find good writing advice an unlikely place. In my case, it was in a fortune cookie (and no, the "in bed" trick doesn't apply here). The fortune said "Four basic premises of writing: clarity, brevity, simplicity, and humanity." Sure, there are several small elements that contribute to an effective and saleable manuscript - plot, characterization and pacing, to name a few - but the fortune's got great advice for a story as a whole.

Clarity. This is especially true for genre fiction or when you're working in a world different than mainstream society. It's one thing to have a concept from your story make sense to you, but will it also make sense to a reader coming from a completely different background? If you're writing a family drama, have you taken the time to explain the hows and whys to your reader? It might be perfectly ok for someone in your story to marry a first cousin, or for a grandfather to legally adopt a step-grandchild, but unless you've been clear in explaining the social norms of your characters or setting, the reader can be lost. Similarly, if you're writing in an exotic science fiction setting and a character is able to jump off a cliff and land softly at the bottom, you better be sure you have explained the physics of the world.
That's where brevity comes in, though. While many concepts and plot points need to be explained to a reader, an author has to be careful to keep the data dumps to a minimum. Tell readers what they need to know, but nothing more. Just because you've done hours of research and have a thorough understanding of a subject, it doesn't mean any of that will help advance your plot or enlighten your reader. There could be incredibly detailed socio-political entanglements in your story, but all the reader might need to know is whether the main character is a king or an elected official. The author needs to be thoroughly versed in the story's nuances, but the reader rarely does.
Similar to brevity, simplicity is a good reminder that it's often the simple explanation that works best. You can write about a stunning sunrise that cycled through every color in the rainbow, but unless it advances your plot, just mention that the sun came up and get on with it. A character watching a sunrise just for the sake of watching a sunrise is rarely interesting, but a sunrise made spectacular by the smoke from a wildfire - a wildfire that just destroyed the main character's home - is incredibly relevant. One simple scene with that character watching the smoky sunrise can convey so much more than a lengthy explanation of the character's every thought that morning.
Which leads to humanity. Stories are most compelling when readers are involved with a character's life. There has to be a human angle. Not all characters have to be likable - afterall, where's the drama without a good villain? - but the story should still explore elements of humanity. That's the source of good drama. Getting inside a character's head, whether they are good or evil, is what draws the reader in to the story. The concept of humanity can explore both the good and bad sides of human nature, and if done well, will leave reader thinking about your words long after they are done reading.

I carry the "clarity, brevity, simplicity, and humanity" with my laptop computer, and it's a good reminder every time I open up a file and start writing. For those who are curious, the rest of the fortune reads, "Lucky numbers 5, 14, 34, 6, 4."

Good luck with your local lotto.