The most important thing to remember when choosing a real estate agent is that this person is about to represent you in one of your most important financial decisions, whether you're buying or selling a house. So pay attention! Check references, talk to former clients and always ask to see their real estate license, which is required in every state. Also, look for good chemistry. As a buyer or seller, you will be spending the next 30 to 90 days with someone with whom you can work comfortably and effectively.