While submitting my short fiction to various markets, I noticed that some markets required that all submissions be sent in proper manuscript format. And although there are plenty of places that are less picky, I feel that submitting your material in this format makes it look just a little more professional. Fortunately, there’s a great website out there put out by William Shunn that gives a great guide.
Hope you find this useful! I’m currently translating my work in process (LD2) over to this format.