One of my friends on Twitter recently posted an article about how some publishers and agents are out to screw the authors for their personal benefit, and others are out there to help you.  The article is very good (well, it's actually a blog post) and points out one example of an agent who seeks the benefit of his clients, and also some of the dirty tricks played by publishing houses.

This is only applicable to you if you go the traditional publishing route with a big house or agent, but it's something you should still be bluntly aware of should you publish with ANYONE, or submit your book through any kind of agent.  There are a lot of publishing houses and agents out there who ARE NOT looking out for you or your personal benefit.  They only care about making money, and they will use whoever they can to achieve that.

So be careful when you publish.  Don't be afraid to research your future publisher or agent should you decide to sign with them, or even submit works to them.  Yes, it's a lot of footwork, time, effort, and sometimes money to do that, but this is your book we're talking about.  It's just like having children. You wouldn't hand them off to just anyone without first knowing who they are and if they can be trusted and will look after yours and your children's best interests.  So why would you do anything less for your book?

So read, research, and find out who are the best publishing houses, agents, and even the best markets for your book before you ever take the leap.  You'll be glad you did.