While there are no guidelines I can give you that will guarantee manuscript acceptance, I can point you in a direction to begin submitting your short fiction. When I first started sending stories out I was totally lost. I just searched for Horror Magazines online and in bookstores and then read through them with much disappointment. However, through the years I've found quite a few resources and will link them out below.
Before you start shopping your manuscript around make sure you have it ready to go. That means it has to be formatted properly (general manuscript format guidelines can be found here but check each publisher's guidelines before submitting; if there is enough interest I'll put up step by step instructions for MS Word). Make sure you have all the typos out of it, this could kill your chances quick if too many are hiding in the lines. And Make sure you read the magazine or e-zine where you are submitting your piece! If your piece doesn't fit the market you are wasting your time, the editor's time, and the other writers' time.
When submitting your work many people would recommend a top-down philosophy, first submit to the highest paying markets and work your way down to the markets that pay only a little or nothing. This is a pretty good idea however I recommend submitting the piece to the market where it fits best. If that doesn't work, focus on the next best fit. You should always get something for your writing (even if it is just copies or products you've reviewed) but if you really just want to see your work in print there are plenty of magazines and e-zines that take just about everything.
Speculative Fiction Multi-site listing:
Ralan's Webstravaganza – This is a great resource for anyone who writes SciFi, Fantasy, Humor, Adult, or Horror. The markets are broken down by pay rates from Pro ($ 0.05/word or better) to 4theLuv (nonpaying). Also Ralan has all kinds of sites that are helpful to writers.
Horrorgenre.com Magazine Listing – An alphabetical listing of all magazines and e-zines that accept horror stories.
SFWA market listing – An alphabetical listing of paying markets that accept Sci-Fi stories and/or articles.
Free Market Search Engine:
Duotrope's Digest – A great free market search that allows you to filter your searches for all types of things such as: Genre, pay, theme, length, medium, and submission type. You can register for a free membership where you can contribute to the reports on things such as response times, the percentage of rejections and percentage of acceptances, and the type of rejection personal or form.
Websites for a few top-paying markets:
The Paris Review – A wonderful literary magazine that (I believe) pays pro rates or better.
Glimmer Train – Literary magazine that pays $700.00/per story
Zoetrope All-Story – Literary magazine that pays $1,200.00/per story
The old standby has been Writer's Market (which is about $30) and The Literary Marketplace (which is way expensive). Writer's Market also has a website with a search engine if you are a paying member. If I remember correctly it is around ten dollars a year. But their search engine isn't so great. It's cheaper and easier to pick up a used copy of Writer's Market and flip through it checking websites to make sure the magazine is still open.
I hope this was helpful and starts you off on the right foot. I'll throw up some more posts dealing with where to start with nonfiction, book, and art submissions in the future.