Organize and make copies of all the documents and information you will need. These should include the deed to the house, proof of title insurance, proof of homeowner's insurance, a property survey, a floor-plan with dimensions, a list of any appliances or other items that you intend to include with the house, and the basic information on your mortgage company. Draw up a list of all your home's best selling points, as your agent may not notice all of them. Not all of these documents are absolutely necessary, but if you have them handy it will save you time later on.
Find a real estate agent you are comfortable working with. Don't just go with the first agent you meet. Interview several agents. Pay close attention to how they present themselves, how they interact with you, and also to how well they know the market in your neighborhood. This is the person who will be marketing your home, so they should make a professional impression. Be sure to ask them what kind of resources they have, and what marketing methods they prefer to use.
Make a list of all the questions you have, and ask your agent to go over them with you in as much detail as you need. This is his/her job. The better you understand the process, the easier it will be.
Fill out a disclosure. Your agent will provide you with this form, in which you are legally bound to disclose any problems that you know of in the house. Be thorough and honest. If a contradiction comes out later, it could cost you a sale, or possible even get you sued. Be aware that you are not responsible for problems that you do not know about. Thus, if you have never used your fireplace, or have never looked under your floor boards, then you are not required to inspect or test them now. In this case, simply say that you do not know, and leave it at that.
Decide on a listing price. Your agent will almost certainly suggest one, but if you disagree, you have every right to set your own price.
Heed your agent's suggestions about staging your house. Assuming your agent is experienced, he knows a lot about how to make you home look as good as possible to buyers. Thus if he/she suggests that you remove certain pictures and other personal items from view, then do so.
Come to an agreement with your agent on how showings will be handled. Will they be made by appointment, or will the agent be allowed to come by with only a few hours (or even a few minutes notice)? Will you be doing an open house? It is best to get these questions settled right away.
Always plan to be out of the house during showings. It can make potential buyers uncomfortable if the owners are looking over their shoulders during showings.