Basic Principles

Relax and sink;
 
Soften or round the joints (like the soft curve of a bow);
 
Empty and full (where the weight is and where it is not);
 
Align shoulders, hips, knees and ankles;
 
Expand and contract according to your body's ability and shape;
 
It is okay for it to be a bit uncomfortable but it should NOT be painful;
 
Coordinate breath with movement;
 
Laugh and be light - an overly serious attitude is like slow poison and will promote frustration and anxiety.  Enjoy the process of getting to know yourself and all levels of being that Tai Chi opens you up to;
 
DO NOT BE OVERLY CONCERNED WITH FORM OR THE WAY IN WHICH FORM MANIFESTS ITSELF, PAY ATTENTION TO THE ENERGY AND INTENT (yours or those you play with).
 
                                                                                  - excerpted from: World Tai Chi Instructor Manual by Peter Hill