Success. To make sure your writing stands the best chance of success, always follow recommended submission guidelines and address your work to a named individual. And even though you will get rejected, by repeatedly trying, you will all the time be improving your skills and increasing your chances.
Title. Never under-estimate the importance of a title. As Raymond Chandler wrote, 'A good title is the title of a successful book.' If titling an article, think of the benefits the reader would gain or an intriguing way to capture their attention. And similarly with fiction, arouse curiosity. Your title needs to appeal and draw the editor and reader in and is worth taking time to get right.
Understanding. When you write, make sure you understand the message or theme you want to convey. By having this clear in your mind and understanding the purpose behind your work, your writing will be far more powerful.