Hire a great lawyer
My husband and I recently sold our co-op and bought a house (in two different states). We had a great lawyer for the house, but the lawyer that handled the sale of our co-op wasn't as great as we had hoped. He didn't return phone calls and I felt that he didn't really have our best interests at heart (and he came recommended by our realtor). If I had to do it over again, I would have collected recommendations from several people and called around until I found someone I felt more comfortable with. We were in a rush, but when it comes to this kind of financial commitment, you don't want to make a hasty decision.