What is the first thing I need to do if I am buying or selling a house?
You may want to find a real estate agent, or broker, to help you in either buying or selling a house. If you are a potential buyer, you can work with any number of brokers.
If you are a seller, you generally will responsible for paying the broker's commission, and generally list with only one broker. Although as seller you list with one broker you'll want to make sure the terms of your listing allow other brokers to show the house to potential buyers.
In such a case, the commission is shared (often split) between the listing and selling brokers. If you are buying a house, you should be aware that the brokers (even "your broker") are almost always acting in the interests of the seller. Sometimes you may even be asked to sign a document indicating this.
If you are selling, you need to thoroughly discuss and disclose the history and physical condition of the house. If you are buying, you need to be certain of your financial ability to pay the price.