Studying a certain area could be studying the spiritual messages, the 'real world' messages, the astrological associations, esoteric symbolism, numerology or Kabbalah. ....don't panic, you don't need to study any of these to be a good reader.
Kitchen Table Tarot is one of my current favourites. Books are important, they help you grow as a reader and keep you open to new insights /perspectives. Even the most experienced and knowledgeable professionals continue their learning by reading on the subject, so read as much as you can (tarot blogs are great resources, Greylady's Hearth is fabulous).
The best way to learn though is to read the cards, practice, practice, practice, this is what out monthly tarot challenges are designed for. If you find you're stuck on an interpretation you can post it here with your ideas and ask for input from other members.
Just remember, it is a life long learning experience, you will never stop finding new meanings for the cards.