Do your homework about where to send your stories. Find out what magazines are interested in, either by reading their entries in Novel and Short Story Writers' Market or by browsing libraries and bookstores and even buying and reading an issue or two. That's far-fetched, but there are magazines about juggling, UFOs, Kansas, jazz, lesbians, just about all religious sects, and a host of other special interests that might be part of your stories. In any case, don't waste time and postage by sending stories to magazines for whom they're clearly inappropriate. Obey the instructions in the guidelines concerning format and length.
Magazines are poor, and editors are justifiably stingy with their time and money.
Besides, you should be professional and polite, and that means enclose a sase. Write back to editors when they reject you, especially if they invite you to send something else. But don't ever argue with them or ask them to read the same story again. It will do you no good, and it will probably do you harm. Don't bug magazine editors over the phone.