Paul did not have any Old Testament scriptural base from which to operate, so the Athenians had to be brought further along than would Jews. Ethnographic cultural observation will assist to understand a people and find points of intersection for the Gospel. To make the most binding peace, children from warring tribes would be exchanged. As aids to observation, we can look for behaviors that to us are strange. So simple that it is overlooked, we can ask a member of the group for an explanation.
Cultural informants are precious.
Research into ethnographies of the target people can be invaluable. Many are not done from a Christian perspective. Country studies published by the U.S. government are very thorough. They are now on CD Rom discs. Article data bases provide the most current information, apart from shortwave reception of national news services.