This is an attempt to give you some ideas about cautions you should exercise and maybe even some thinking about whether it is such a good idea to take on all these responsibilities yourself. There are some good reasons for having a Licensed Broker or other real estate professional involved. It is not, however an absolute requirement. There may be some people who would take out their own appendix. Now you know where I am coming from and that I am unabashedly biased in terms of involving a professional when it makes sense.
Your friend Joe hasnt been able to use his week at your resort for several years and has decided (correctly) that he should sell it. His price is reasonable and you agree to buy it. Your first step is to make sure Joe owns it. Dont make the mistake of thinking he is such a good guy he wouldnt lie to you. He may be absolutely honest, but we have just had so many cases where people were confused about what they owned, how it worked and what name they had used to acquire it. They may have forgotten that they put it into a trust or believe it really doesnt matter that they did. If the paper work isnt correct you might just as well have a deed to the Brooklyn...