I've worked with many writers over the past fourteen years and this next piece of advice is one I've been wanting to share for a while. And this applies not to my private freelance work, but to work I do with publishing houses, and acquired authors.
Whether a writer starts with me with an agent or gets an agent part way through our relationship, I've noticed that some of these writers use the agent as a middle person, to the extent that they don't communicate with me fully, but use their agent to do that instead.
An agent is supposed to be a buffer of sorts to handle conversations and negotiations that take time away from the writer's writing time or simply because that writer doesn't want to worry about anything else but writing. But when you use an agent to do much of the communicating with your editor, you lose the development of a very important relationship, the editor-author relationship.
The building of a close working relationship with your editor is critical to developing a great book, I believe. The authors who are most open with me, talk to me about everything, brainstorm etc are the ones I have the best relationship with.
I hate talking through an agent. I feel disconnected from that writer when I do, when I'm forced to. It makes perfect sense because for any relationship to work and grow you need to communicate directly with one another, and if that element is missing then how can you expect it to go anywhere? It stagnates and fails to flourish.
So if you're in the position of having an agent, or are about to get one, really think about how you want to use that agent and think twice if you want that agent to do all your communicating for you. Keep that editor-author relationship open and free, unhampered by a third party.