There are good agents and bad agents. A good agent can help in two areas:
[li]Knowing what editors are looking for and what they see too much of[/li][li]Negotiating a contract[/li][/list=1]
If the agent knows the markets, the marketing isn’t as hit or miss. A good agent should know that Stupendous Books is overstocked on vampire novels and won’t sent your vampire novel there. At the same time, in a lunch with the editor of Charnal House, the editor told the agent, “You know, we hardly ever get any good vampire novels any more.” If you were doing this, you might try Stupendous Books, and send to Charnal House later, by which time the smart agents have given them all the vampire novels they need.
And no first-time writer should go into negotiations without an agent. The publisher has plenty of experience negotiating contracts; you have none. Guess who’s going to get the better of the deal? A lot of editors, when they buy an unagented novel, strongly suggest you get an agent to handle negotiations. Overall, the extra money and the protection of your rights is worth much more than the agent’s cut.
But a bad agent can certainly harm your career. And even a good agent may not be the right agent for you.
It’s also untrue that agents only represent books that “make whacking great gobs of cash.” They will represent any book they think they can sell. As long as they think they can make money from a sale, they’ll be interested in taking you on. Most will be happy with a few hundred dollars in commission for a first book, since once you’ve sold that one, you should be able to sell more. Agents would love to be able to handle an author who can sell one book a year for a solid advance. A good agent wants to represent your career, not just an individual book.