Be Mature

In contrast with the U.S., the legal drinking age in Spain is 18, except in the province of Asturias, where it is 16. 
Be mature:  Don’t be the ”ugly American”. Spanish students your age are accustomed to having beer, wine, and other alcoholic beverages at home and outside the home with family and friends.  They tend to have a totally matter-of-fact relationship with alcohol.  American students who act like children in a candy store when freed from our laws seem foolish and immature. 
Be careful!  Many of you will not have lived with unrestricted access to alcohol.  Spain and Andorra are very safe countries,  but no place is safe if you are drunk and unable to assess your surroundings competently.  If you must drink, do so judiciously; do not get drunk.  There an be serious consequences and put your safety at risk.  Crossing traffic-clogged streets carelessly, interacting with people you would otherwise avoid, and increased risk of falls can all be avoided with a little common sense.