To write a good book you must have all the bricks in the wall.
Constant learning prevents cobwebs in the brain
Writing a book is a long hard process, and a lot of work. I used to think that the most important - actually the only - thing involved in writing a book is sitting down and writing it. Well, that is kind of important, and the story is key (D'uh) but it's not the only thing.
There are so many things to consider and to work on both during and after the initial writing process. I consider myself to be a reasonably good writer - much better than I used to be, and I try to keep the rules in mind when I'm writing. Yet I still get manuscripts back from editors which are (relatively) full of red ink. And that's a good thing.
Surely, we've all heard of 'nose blindness' by now - that is the inability to smell how bad something is when you've been living with it for some time (think teenage boy's room). Authors on the other hand, suffer from word blindness - that is the inability to spot the odd misspelled word/typo despite having read it three or four times. We are also notorious for forgetting that readers don't know our stories and characters as well as we do, therefore need to be told things we have grown to take for granted. For example, say a character gets sad when watching a mother with a child because he lost his mother when he was a child, it would be helpful to let the reader know that fact at some point or they will completely miss the poignancy of the observation.
When writing words such as 'clearly' and 'obviously' we need to ensure that the reader knows what is obvious or clear to the characters, and the writer themselves.
Another thing authors need to be very much aware of is basic grammar. I'm the world's worst at commas. I really am - to the point I never question my editor's placement of commas because I wouldn't know if they were. And I have my own blind spots, of course I do. I'm far, far from perfect, but there are some rules that are so basic I literally cringe when I read them, and I see them all over the place (Even J K Rowling is not immune)
In particular I'm grinding my teeth at the moment at authors who don't know the correct way of using lay and lie. If I read that someone is going 'lay on the bed' one more time I'm going to scream. If you're talking about something that has past - yesterday I lay on the bed for a nap - that's fine, but you can't say - I'm just going lay on the bed for a while! It's - I'm going to lie on the bed.
For a brief explanation see here where I also talk about the whole its/it's issue
I'd like to shoot the person who compounded this conundrum by making lay the past tense of lie.
Some other pet peeves I would like to whinge about are:
They're - the apostrophe always denotes a missing letter. So ask yourself is there a way to put another letter in there? If the answer is yes then it has to be they're (they are) These words are called contractions because they're the shortening of two words. Other contractions are it's (it is) I'm (I am) and I'll (I will)
Their - belonging to them.
There - a location. Nothing to do with them at all. No one can shut there mouth because there doesn't have a mouth, There are no mouths over there. Their mouths are all in their faces over there.
You're - you are, Again two words squidged into one, therefore an apostrophe for the missing ones.
Your - belonging to you. One word therefore no apostrophe.
Sometimes it seems I spend half my life checking grammar and looking things up in the dictionary, so I know it's a pain, but it's worth it.
The moral of the tale - never, ever publish a book without other people reading it critically.