As a writer, we are invested in ourselves - the pleasure of writing, of creation. Deep into the world-building and narrative structure of our stories we, the writers, can have a hard time understanding this. We sweat blood and tears to produce our work. The least that ungrateful wretch could do is hang in there and see the story through.
It's harder than most writers appreciate.
Readers have it so easy
Look at that reader! Curled up in a comfy chair with a glass of wine and an hour or two to be entertained. They get to kick back and have a good time. Unlike the poor writer who stayed up until 2 a.m. trying to figure out how to cut those last seventeen words out of a short story to make the 1,000 maximum word count.
What the reader wants is something that will keep their interest, that is evocative and compelling. They want a story that will keep them up until 2 a.m. to find out how it ends. They're invested. Once you've got someone hooked that far, you'd better make sure the payoff at the end is good. Really good.
Let's say the story premise is really interesting, but the writing is not so good. Our valiant reader sticks with it. They read all the way to end because they are interested enough to find out what happens. In this case, the payoff at the end better be more than good. It better be spectacular.
The more you ask of a reader - slogging through flat, one-dimensional characters, typos and stilted or rambling writing - the more they expect as a reward for hanging in there.
Think of as asking someone to backpack up a mountain. As the writer, you get to decide how steep is the mountain, how heavy the pack. You also get to decide what's at the journey's end. If you ask a reader to carry a Volkswagen on their back up Mt. Everest you'd better make sure there's a breathtaking view and not a McDonalds. They didn't need to climb your mountain to get a Big Mac and will be understandably disappointed.
Make sure you, the writer, are as invested in the reader as you are in yourself.
There are myriad places to turn to for help. Notice, as you do, that the advice is consistent.
Open the story with a compelling hook, not backstory
I will raise my hand on this one. I'm guilty and this is a guilty pleasure for me that does not translate into goodness for the reader. When I write a slow opening it's usually because I want to gradually unveil my characters and world. That would be nice except the person I'm gradually revealing this to is: me. Not the reader. I'm description the character's hair color, eyes, backstory, etc. as a way of reaffirming the story to myself. A reminder, if you will. Too bad reminders and backstory belong in story background notes or page 10 and beyond. Backstory can be extremely important if it justifies what's happening in the story. But later, not at the beginning when I'm trying to get your interest.
Show the reader what's happening rather than telling
Give them a world to step into. Give them characters and a story they can discover on their own with wonder and astonishment. Don't give them a synopsis where you explain what they should think. If that was such a great way to tell a story, James Joyce could have just published Cliff Notes.
It's easy to write a story in haste. As the writer, you know what you want to say, but a reader doesn't know what's in your head.
Make sure there is nothing to distract from the story
Typos, poor grammar, rambling sentences that are difficult to read. Obscure language and words the average reader has to look up. You want the reader unable to put your story down, compelled to keep reading to the journey's end. Anything that takes them out of the story is bad. It's like going to a movie theater and having it stop right when the action is good to tell you the next bit will be in 3D. I like 3D movies, but right then and there I'd rather watch the rest of the movie than run back to the lobby to get 3D glasses. Especially if I do it, come back, and find out I only needed 3D for the next 5 minutes of a 90 minute movie. And it wasn't even 5 minutes of critical story that had to be in 3D.
Don't use more words than absolutely necessary
Words are like children. I love all of them. Being asked to get rid of something I spend days/weeks/months/years putting together is painful.
As a writer, I hate it.
As a reader, I love it.
If something does not contribute to the story in a meaningful way, get rid of it. This reminds me of a quote attributed to the famous Renaissance artist, Michelangelo. Asked how he was able to sculpt such amazing masterpieces like his David, he said:
It is easy. You just chip away the stone that doesn’t look like David.
Look at your words with a critical eye. Will a reader be unable to understand what is happening if it was gone? Would our intrepid reader throw down the book and say "Damn it! I wish I knew she ate bacon and eggs for breakfast! I'd have understood everything!"
When you fill up your reader's backpack with characters, backstory, plot, scenery and all of the other minutiae of a story, ask yourself, "Are they carrying a Volkswagen up a mountain? If they are, make sure they get an amazing view unavailable anywhere else and not a Big Mac."