You can't build a house without the proper tools and the same goes for writing a novel. You need to make sure that you know the tools of the trade, just like every other profession. Not only will it help you tell the story you want to tell, but it will keep you from looking unprofessional when that time finally comes to query agents/publishers.
Spelling. Punctuation. Grammar.
I've had a few people ask if it's important to know all that stuff. My response is always yes. It most definitely is. You don't need to know it so well that you have a degree on the subject, but you at least need to know the basics. The rest comes with time, experience, and if necessary--schooling.
Because really...what would you want to do if you came across something like this?
Josie was a pretty gril.She hda lung dark hiar and bg blue eeyes One day she; wondred wht it wuld be like too flie. 'Sum day i will" she says. and then wen't home.
Don't laugh. That was incredibly painful for me to type.
Do you see my point though? I don't care about Josie or what pretty blue eyes she has. I don't care why she was wondering about flying. All I saw was an author who has no clue what they're doing. And that doesn't make me want to keep reading...It makes me want to pull my hair out. If something like that ever made it onto an editor's desk, he/she wouldn't even look past the first sentence, let alone the first page. There is no room in the publishing world for writers who don't bother learning their craft.
There is no excuse for bad spelling. There are a number of programs with that wonderful little Spell Check button. Of course, I'm not talking about a few misspelled words here and there that escape your notice. It happens. I'm talking about completely ignoring the obvious and thinking it's okay to do so.
Learn where to put your commas, your apostrophes. Click that little button if need be! There is no shame in it.