Here is a very important concept to incorporate in your Tai Chi training with a partner.

What is the meaning of rollback energy?
Entice the opponent toward you by allowing him to advance,
lightly and nimbly follow his incoming force
without disconnecting and without resisting.
When his force reaches its farthest extent,
it will naturally become empty.
The opponent can then be let go or countered at will.
Maintain your central equilibrium
and your opponent cannot gain an advantage.
(Tan Meng-hsien)