Some authors spend a ton of time describing the leaves of trees and the way the grass blows in the wind. That's all well and good, but don't ever forget to include the details that matter.
When I was a little girl, I found the plot of Star Wars to be incredibly confusing. This is because I thought they were saying that Luke's father had gone to the dark side of the forest. I was always like "well, maybe he got lost." It took me a long time to really understand the plot of those movies, and it's not even my fault. The storyteller should have made it more clear.
It's your job to make sure no one is thinking that about your books. Sometimes when I'm writing, I get into a zone where the words are just pouring out. I don't even have to think about them, half the time. And I might slip into all sorts of slang and colloquialisms. Then I go back and read what I've written and I realize that I'm the only person who knows what the hell I'm talking about. So then I have to add the details that matter.
As an author, there are some things you're going to have to explain. Don't assume that everyone knows about franks and beans, or that they'll understand why the British character just asked for a "fag." (Do not send me a bunch of angry emails; I'm told that in England it means cigarette. This is why it's necessary to add the details, you see?). When you're writing, look for the potential land mines -- and make sure you've added the relevant details.
- Locations: Where you come from, everyone might know about Chimney Rock. But if you mention it in your book, make sure you add basic details so I know it's a tall, skinny pillar of stone that looks like a stovepipe. Even the most famous places should be described and fleshed out. Tell me who the Statue of Liberty is, if you're putting it in your story.
- Wardrobe: And I hope you'll all take this seriously. Not everyone knows what every piece of wardrobe is called -- lookin' at you, Mary Higgins Clark. You know I love mysteries, but I have read so many of her books where I'm just sitting there screaming "what the hell is a kaftan?" It's something her characters wear all the time, and it drives me nuts. If you're going beyond the basic pants, dress, skirt or shirt, give me the details!
- Food: Always explain your food. Cuisine is so regional, people less than 50 miles from me have no idea what real biscuits n' gravy is (the heathens). So if your characters are having something like hot brown or chipped beef or grits, you'd better tell your audience what the heck that stuff is. Don't be cute about it -- most people are going to know that a steak is a slab of beef, but not everyone knows what a lobster bisque is.
- Slang/Text: Hopefully your books will be read by people of all ages. When this is the case, you may need to explain certain slang, sayings and text messages. Try to do this without interrupting the flow of dialogue or the narrative.
How do you know what you need to explain? Pretend you're writing your novel for an alien. They don't know your culture or your setting; you have to describe it to them in a way they can understand. Remember to write the details that matter, and you'll be a better writer.