A business book author just asked me whether he should sign with a particular agent. I turned the question back to him by responding:
Basically your decision should be made on a combination of (in order):
1. Her recent sales (whether she is doing the job now as evidenced by recent book deals to publishers you admire);
2. Her client list (whether she already works with people with whom you want your career associated);
3. The quality and success of the resulting books (how you feel about the final outcome… what is published and how it does);
4. How you feel about her personally… whether you communicate well and enjoy working with her.
All literary agents should be willing to give you an exact list of deals they have done in the past couple of years, and also a list of whom they represent. These are tangibles… they are quantifiable, and you can learn much about an agent just from them. However, the last two points are more intangible. How do you feel about the books that resulted from those deals? Are they bestsellers? Midlist books? Do they reflect your vision for your own career?
I listed how you feel about the agent last, even though many authors place it first. Some authors go on and on to me about how much they love their agents, even if those agents haven’t had a deal in many months. Meanwhile, I personally care more about results than how much I like an agent. There are abrasive ones out there, though, and although I try not to weight the personal factor too much if the agent is making successful deals, there are some agents I have put on the “Do not query” list because the personality issues just aren’t worth it. Fortunately there are many successful agents who are also highly professional–the best of both worlds!