The best ways to pick a good one are to get referrals. If you needed open heart surgery what would you do? You’d ask around everyone you knew to find the best dr. When you embark on the biggest single purchase of your life why would you do anything less?
I would also be leary of anyone making huge claims that they can do what no one else can. There are lots of skilled people out there who can get the job done right. If the person looks a bit too slick beware!! The key is to find someone who is skilled and will put your best interests first. The internal conflicts in real estate sales are enormous and this is a very difficult thing to do.