Most, if not all, traditional publishers/editors/agents will tell you that before you do anything, make sure your story is complete and polished. If you're only on your first or second draft, focus on revisions before attempting any sort of publication. If your manuscript is ready, then I highly recommend the 2012 Guide to Literary Agents (Or whatever year is newest). Not only is it a great reference for building query letters and learning about the industry, it also has a section in the back dedicated to agents who are looking for each specific genre. Another good resource is author J. A. Konrath's website. He has a free book you can download that is all about the writing process and getting published. I don't personally recommend self publishing, because it instantly locks your book out of libraries and retail book stores, but I do acknowledge that traditional publishing is harder to get into.