As a senior, you must shop around to find the right teacher, someone who is sensitive to your special needs. There are many excellent teachers of Tai Chi who do not know how to teach seniors. An older teacher is probably better than a young one. He or she probably understands your needs.
Tai Chi can even be taught to those in a wheelchair.
Find out how long the teacher has studied Tai Chi. Does he or she have any credentials? Certification? It is equally important that the teacher has a background in working with people such as a high school teacher or a psychologist.
Steer clear of teachers who emphasize the martial arts aspects of Tai Chi. Their style tends to be too hard and physically demanding for most seniors.
Many teachers move too fast through the sequence of movements or gear their classes to the fastest learners. Visit Tai Chi classes and choose a teacher who goes at a speed you can handle easily.
There are short and long forms in Tai Chi. Be certain the teacher is teaching one of the short forms.
Observe a class to see if you feel comfortable with the teacher's explanations. Can you hear him or her easily? Does the teacher take enough time to be clear?
Ask the teacher if you can try out a class. I allow anyone to take the first class for free.
The cost of the course should be reasonable without requirements to buy special clothing or books. Tai Chi is the ultimate low-tech exercise, requiring only your commitment to learn.
The best scenario is to find someone who has special classes for seniors. YMCA's or senior centers are the primary places to begin your search.
Good luck.
See Arieh Lev Breslow's previous article, Tai Chi for Seniors - Chapter 1."