Today is a link salad from agents about query letters, the cost of publishing, and what to ask an agent.
Finishing your book and deciding you want to get it published is only the first hurdle in a long marathon. Unfortunately there isn't a nice track either. There are side roads, many that lead into nowhere. So what is an aspiring writer to do? Here is a great link from Writer's Digest on 10 things to do before you even send your query letter out to agents:
http://writersdigest.com/article/Ten_Things_You_Should_Do_Before_Trying_to_Find_an_Agent With querying comes a lot of rejection so be prepared. Be sure to check out great agencies like the Waxman agency. I love what they say about rejection:
http://waxmanagency.wordpress.com/ And read up on other great blogs like Chuck Sambuchino's editors blog. Here he gives advice on what to say and what not to say in a query letter: http://www.guidetoliteraryagents.com/blog/20+Tips+On+Query+Letters+As+Told+By+Agent+Janet+Reid.aspx
You may want to check out agent Rachelle Gardner's post on whether or not your book is worth it. She breaks down the cost of creating a paperback and a hardback book. It's a real eyeopener and, it will give you an idea of how many books you'll have to sell to make your advance back for your publisher.
Once an agent makes an offer take a deep breath and ask questions before you accept it. Finding out what their plan is for your book is vital to having a healthy working relationship with them. Despite the barrage of questions I asked my agent, this one, suggested by literary agent Janet Reid, didn't occur to me: http://ow.ly/ArjY
Best of luck!