Any successful magazine writer will tell you that query letters are the key to breaking in to the business.
In a query letter (these are increasingly emails rather than hard-copy letters), you pitch your fantastic story idea to an editor and request the opportunity to write the story for them. Over time, as you get more established, editors will get to know you and will increasingly assign stories to you directly. But when you're just starting out, queries are a must.
It's vitally important to develop a thick skin, especially in the beginning - you're going to get a whole lot of rejections, no matter how good your ideas or writing are. But here are some ways you can increase your odds of getting a yes:
1. Know who you're pitching to. There's a ton of turnover in the magazine business, especially these days. The editor whose name is on the masthead of the current issue may have actually left weeks or months ago. It's always a good idea to call and confirm before you send your query out. And don't try to cop out by writing "Dear Editor" - it's lazy, and editors hate that (they will think, fairly or not, that if you can't even be bothered to find out their name, you're probably not much of a reporter).
2. Know the pub you're pitching to. If you're not a regular reader of the magazine you're pitching to, it's a good idea to go to the library and check out a few recent issues. Look for:
--Which articles are written by freelancers vs. staff (staff are listed on the masthead)
--Regular departments where your story might be a good fit
--Whether or not your idea has recently been covered
--Writing style (first-person vs. third-person narration; formal vs. informal tone, etc.)
3. Know your slant. It's not enough to tell an editor that you want to write a story for them about weight loss. You need a specific slant, e.g., "9 Ways to Lose Weight While Napping" or "How I Lost 38 Lbs. Eating Nothing But Bananas."
4. Don't hide the ball. The editor is not going to steal your idea. Promise. So don't be cagey - you need to explain enough about your idea that the editor is intrigued, can envision where the story might fit into the magazine, can see that you've thought through the details and length of the story, and, most importantly, can see that you can be trusted to write it well and deliver the goods.