AS ATTORNEYS for a range of art-collecting clients, from those who merely dabble in the market to those who have made a Gagosian amount of money buying and selling art, we find that we give the same ironclad advice over and over: Your art investment is potentially worthless if you fail to protect it legally. Moreover, without the proper protocols in place, you stand to lose more than your purchase price in the event of a legal challenge. Many pitfalls, from issues of authenticity to ownership disputes, can be avoided with proper legal procedures. In the hope that you end up like Larry G-and not as a cautionary tale in one of our future columns-we have answered a few of the most common investment-related legal questions from our e-mail inbox.