There are a million articles out there that will tell you how to create a fabulous submission package. You can read those and they might help with improving your package. There is one thing you have to do in order to get your foot in the door.
READ THE DIRECTIONS
Carefully and thoroughly read the directions. Follow them to the last minute detail. Don’t assume you know better than the editor / publisher. If they provide a style sheet follow it. If they provide specific fonts, font size, margin width, double vs single space, follow their direction.
Editors give specific directions for their own reasons. It may help them through the printing process better or it may level the playing field when comparing different submissions. It doesn’t matter why. If you want your writing to be considered then follow their directions to the last detail.
Submissions always take time for me for this very reason. One thing I try to do is put the title of the item in the subject line of the email. If they are responding back it helps me to know which items they are referring to. However, if they have specific directions on what should go in the subject line make sure you follow them rather than my tip.
Ultimately you want your writing to be as pleasing and readable as possible for the editor. You want to be that annoying student at the front of the class, raising your hand and getting their attention for your good work. Following their directions will let your work stand on its own rather than have it be another poem (short story, essay or whatever) in the wrong format.