Read! This will expose you to the theories and concepts of dog training. Select from different authors and subjects to get a variety of perspectives.
Learn what methods are popular now as well as how dogs were trained
from a historical perspective.
If you are not already in dog class, get yourself back in an upper level class. This will sharpen your skills. If you do not have a dog right now, borrow a friend's dog or put a shelter dog through classes.
Set
a goal with your own dog. This will help you to reach a level of
proficiency in your area of interest that will give you insights
helpful in working with others. It will also get you involved in the
dog training community helping you establish contacts.
Find a training school(s) that you like and volunteer in return for observing. Watch and learn. Find out how you can assist in classes. Get your feet wet.
Go to your area animal shelter and volunteer to work with the dogs. There is nothing like experience with dogs you don't know to teach you to be a great trainer.
Go to
LOTS of seminars on behavior and training.
Subscribe to magazines.
Consider joining a dog training club or professional organization.
Go to dog trials and shows that feature performance events. Watching dogs compete can teach you about relationship dynamics, training techniques, breed specific behavior, body language and more.
Learn
about how to teach and manage people in groups. Your ability
to connect and communicate with the owners will go a long way toward
helping the dogs.