Choose 3-5 based on recommendations, reputation, and knowledge of your area AND neighborhood (very important). Interview these 3-5 realtors--prepare the questions that are important to you. It's business; you should not be looking for a friend, but someone who will do the best job for you. If you have trouble with the interview part, act as if you are working for someone else and getting the best person for them. I find that helpful in looking out for my own interests.

Good book: 100 Questions Every First Time Homebuyer Should Ask. Even if you are not a first time homebuyer, you might find it very useful.