I've been looking over some student manuscripts lately and the most consistent problem has zilch to do with creative writing, per se. Yet this problem might keep a story from being published.
I'm talking about the format of the manuscript. Think of it this way: you'll be sending that manuscript out on job interviews. Dress it appropriately and you increase the odds that your baby will land a nice position someplace.
Or, hey, think of the standard format as a secret handshake. You want to be considered a serious writer? Your manuscript had better look as if you're one of us and not an imposter. At least, that may be what potential publishers think.
Good reasons exist for using standard formatting:
1 - A font that takes up the same amount of space for each letter will always put the same amount of characters on a page. That makes it easy for an editor to tell at a glance how many published pages your story or novel will need (meaning, yes, they can then tell if you lied big time about your word count).
2 - Publishers ought to know exactly to find your address, phone, email, word count. They shouldn't have to guess if you're using a pen name, or for that matter, what name to put on an advance check. And it's just plain common sense to put your title, last name and page number at the top of each page in case they get separated.
3 - Standard formatting is easier to read and edit. You may think to dazzle an editor with an array of beautiful fonts, but you're merely distracting the eye from what ought to be the real jewel--your story.
FONT: I use Courier New, 12pt. Most computers have that font or one similar. It's easy on the eyes and as stated above, each letter is the same width. Don't make any font bold.
SPACING: I shouldn't even have to tell you to double-space lines. Do NOT put an extra line between paragraphs unless you want to indicate the beginning of a new section, and then put a "#" to show you mean the blank line to be there. ALWAYS indent each paragraph. You're not writing business letters or a blog. Don't play with spacing to make more words fit on a line or more lines fit on a page.
HEADING for each page: Top right-hand corner. Title / Last Name / Page Number.
For more on formatting, like how to do title pages, and to see examples, check out these links:
(A good example except he puts the word count at the bottom of his title page. I put it at the top, right side, so an editor flipping through a pile of manuscripts can spot it easily.)
(A good example of short story formatting.)
Your writing should be creative, not your formatting.