What most people would say is to interview three realtors about selling your house, show it to them, and see what they want to list it for, what they promise to do in order to sell your home, and how well they communicate with you.
But for me, that isn't good enough. I'd first go to some open houses and talk to a number of realtors without revealing that I want to sell at any time soon. Don't encourage any of them to pursue your business, but just talk about real estate in the local area and so on. (Also, you can be getting ideas about staging and so on just from looking at the houses.) It used to be that the big, well established real estate agents didn't do open houses so much, but at least in my area that is no longer true. Even they are doing everything possible to sell homes, including personally handling open houses.