You have already recieved some great answers to your question so let me give you this advise.
Every homeowner who is planning to sell their home should do the following:
1- Interview 3 agents from 3 different Companies.
2- Compare marketing strategies and marketing plan i.e. where and how the market to potential buyers?
3- You want to hire a full time agent ( not someone who does real estate as a second job) you want an agent who lives, breaths and eats real estate.
4- What are their hours of operation?
5- Do they have an admistrative staff to handle inquiries that come in right away?
6- Do they have a system in place?
You may check me out on the web to get an idea of what I'm doing at http://www.irenapopilevsky.com