Paul B. Spence
Writing can be painful. You pour your heart and soul out onto the page and then hope no one comes along and grinds it under their boot. Don't give up. Keep writing. Writing is a skill, it takes practice to do it well.
Rewrite and polish. Polish it till it squeaks. Seriously. Read it out loud to a friend. Have them read it to you. You'll find more errors when you have to actually speak what is on the page, because when you read what you've written, your brain fills in the blanks. It can't when you have to speak it.
Find an editor/proofreader. Make your work professional, before you try to sell it. You'll be happier, and so will your readers.