I'm curious though, tri, isn't that all up to the agents? How can an author battle for a better advance if their agent is the one ultimately trying to make the deal?
The agent is working for
you (in the agent situation). Reputable agents will always connect with their client about money matters, especially advances and royalty amounts. That also goes for auctions and preempt deals. You will always be in the loop. But stress your intention of involvement right up front--
you really shouldn't have to. They are not going to go behind your back and seal a deal without your knowledge.
Believe this or not,
you can set an advance amount once your agent tells you what they're offering. Now, at the very least, you and your agent will come to agreeable terms via compromise at the beginning of the process, and that way you can back out early if you want and leave the negotiation to he agent.
If you want it that way. My advice is to get in there and express your expectations, and your agent is going to listen with rapt attention. The first advance offer will most likely be a standard low-ball figure.
You would never negotiate directly with the publisher over a contract when you're repped. The agent is your mouth piece--you have the ultimate say in the end. Always. You can veto anything. With the A-list/celebrity authors, guess who runs the show there and makes the final decisions?
Writers battle for a better advance when they
don't have an agent. This is difficult because there are not a whole lot of publishers out there that offer nice advances to non-repped writers. You would negotiate with, say, Tor or Baen, or some of the others that have an open-door policy (I'm sure you guys have a list of these). A small press that offers a little or token advance? You could try and push that up a bit, but don't count on it. I actually had a small press auction, if you can believe such a thing. But, I had an agent, and we gabbed back and forth about money like a couple of strong-arm robbers. I decided when to stop it and pick our winner. I have to say that it was funny as hell, but heated.