Typing THE END isn't the end of the writer's job. Not at all, you nod sagely, now begins finding a market for all those lovely words.
Wrong. Now comes the editing process where we make all those lovely words sparkle and shine. There are different kinds of editing. There's editing for content (making sure the heroine's eyes are green all the way through). There's editing for plot (making sure there aren't any dangling plot threads that ought to be tied up). There's editing for grammar and spelling plus a host of other editing jobs we should do before we send our babies out into the world (Seriously, you wouldn't send your children to school wearing their play clothes, would you? Didn't thing so :D )
In this day and age of computer assisted spell and grammar checking, you'd think that this particular form of editing would be a piece of cake. It's not. For one thing, most grammar checkers are just shy of stupid. Their protocol doesn't really reflect the way writers develop sentences or use various parts of grammar for dramatic purposes.
I'm sure you've seen the green squiggles underlining a sentence fragment that you purposely wrote. And if your grammar checker is like mine, you've probably seen is holler about fragments even for sentences that clearly have a subject and verb. The best advice I can give is turn the sucker off. If you need guidance with grammar, either get a copy of Strunk & Whites Elements of Style or go online and review it. It's very helpful.
The spell checker is just a little more user friendly for writers than the grammar checker. But you have to be careful with automatic corrections (as in turn them off). I had a writer friend once whose hero's name was Jonah. She had the auto correct on and didn't realize until she'd sent the mss to her editor that the mischievous program had changed every instance of Jonah to gonad. That was not a good thing, LOL.
Another thing we need to keep in mind is that spell checkers can't differentiate between words that can be spelled in different ways and have entirely different meanings. The best we can do there is to read the mss out loud. That helps us find those words that have gone on holiday someplace other than our manuscript.
Like all writers, I edit until my eyeballs feel like shards of glass are permanently embedded in them. And like all writers, I've sent manuscripts out only to discover I'd dropped a word or had a typo I didn't catch. It's inevitable. Your main goal, though, as a writer is to make your work as perfect as possible.
For a chuckle, and an example of the Impotence of Proofreading, listen to the youtube I've included here. I know none of us have ever made so many and so, um, descriptive blunders. Have a great weekend!