Before you send out your finished article or story, check the quality of your work. Is it the best that you can produce? Have you followed special guidelines on formatting? Does your intended market request larger margins, double or single spacing, a specific type font? Most guideline sheets specify type-written or letter-quality print with a font such as Times New Roman, but some editors request single spacing or a font such as Ariel. Be sure that you pay attention to each editor's preferences.
Proofread for run-on sentences, lazy-writing (e.g. beginning all your sentences with "the" and incorrect word usage.) Have you checked for spelling, punctuation, and grammatical errors? Your computer's spell checker will not recognize the difference between their and there, its and it's, further and farther, or any one of a number of other common errors. Proofread aloud and from end to beginning if you want your manuscript to get more than a cursory glance from a first reader.