Very few literary agents are generalists. They specialize in certain markets and focus on specific genres. When approaching agents, smart authors will have done their research. They know what genres an agent represents; they know the kind of projects the agent is willing to take on. They also know who the agent represents and are aware of the agent's current submission policy.
The place to start is identifying the genre you write in. Be specific. Don't stop at science fiction but dig deeper. Do you write steampunk, cyberpunk, dystopian, military, alternate universe….? You need to understand what you write before you approach agents. Once you have determined what you write, it is time to begin your research.
One way to research agents is a top down approach. Look at online directories like QueryTracker.net and AgentQuery.com. These databases often list the general likes of particular agents and they often include links to agency websites and blogs. You will want to visit the websites and blogs.
Take time to study the agent’s websites. Look at their clients' websites and also read a few of their clients' books. Pay particular attention to the agency submission guidelines. Some agencies are only open to submissions at particular times of the year. Others have strict manuscript sample lengths. If you do not follow an agent's clearly stated rules you are highly unlikely to get a read.
Follow your targeted agent on their blog, on Twitter, and on Facebook. Your research will uncover where your targeted agent tends to "hang out at the water cooler." If you have something to say, join the conversation.
Another way to research agents is a bottom up approach. This approach involves studying books. Read anything that seems similar to your work. If you like the book and sense a true connection with it; follow the trail from the author to their agent. Sometimes authors list their agent in their acknowledgement. Sometimes they list their agents on their websites. You can always contact the author and just ask who is her agent. Many are happy to share this information.
Follow these tried and true paths to narrow your search for an agent and connect your work with someone who can best represent your work.
very helpful and informative article..^_^