In order to determine the right buyer for your land, look at the highest and best use to determine where to start placing ads. If it is country land that is perfect for hunting, look for local outdoor forums and clubs to advertise your land. If it is a good home site, a land broker or traditional real estate agent may be best. You can also contact the neighbors, who may be interested in extending their property.
You can also look to certain companies and organizations that have a concentration of people that may fall in the above mentioned roles such as investment companies (i.e. Charles Schwab, Fidelity), financial advising companies (i.e. Morgan Stanley, Merrill Lynch). There may be a higher concentration of people who can both afford and want to build their own custom homes or to build income-producing properties. Try linking yourself to financial advisors who may already know of people who have these types of dreams. This isn't a comprehensive answer of all the possibilities but just some thoughts. Good luck!