Watch a lot of movies, paying particular attention to the minutiae. Get a sense of how the setting is depicted in the films, remembering that art direction is subtle and not in-your-face.
Encourage your artistic side by working with your hands, practicing sketching and drawing. You must have a good visual and spatial sense, and you must be able to apply them to the look and feel of the film.
Keep an eye out for the world around you. Observe things that are mundane and the seemingly insignificant parts of the world aorundyou. Art directors need to be accurate down to the smallest detail. Try to be aware of everything you see.
Strengthen your communication skills. You’ll be working closely with many people in order to realize the vision of the director. The ability to take orders and delegate responsibility is essential.
Take classes. Art directors wear many hats and combine the fields of art, design and even carpentry. School is an excellent way to learn these skills. It help you to nurture them, and you can also gain invaluable experience.
Nothing beats experience, which unfortunately means you may have to work for free or for practically nothing. Again, school is a good avenue to work on student films or plays, and small regional theaters are always looking for volunteers. The work will give you a feel for how sets are made, and the experience will be an excellent way for you to hone your skills, not to mention meet the right people.
Develop relationships. A large part of working in movies is who you know, and one should remember to never burn any bridges. The connections that you make and maintain will go a long way to getting your foot in the door. It may also open the door for future opportunities
Practice humility. Art direction doesn’t occur in a vacuum, and it requires a person to accept being told what to do and sometimes compromise their ideas. Furthermore, an AD must be willing to accept that all their hard work will be discarded once a movie is done.
Become computer proficient, especially with graphic programs like Adobe Photoshop, Illustrator and Quark Express. Learn to use a good computer aided drafting (CAD) program.