- positioning yourself, your base, in the correct position with respect to the load.
- correct choice of a fulcrum (pivot point)
- correct choice of lever arm
- correct choice of position of load on the lever arm
- stabilization of the fulcrum, so that it does not give
Each situation is different, but some of the methods of doing this in OCIS are counter-intuitive at first. Once you have done the motion until it is internalized, you see that correct leverage is much more effective for delivery of power.
This really needs to be shown personally, on a technique by technique basis. After a while, you will be able to see the commonalities. Most of my deeper understanding on this comes from Chen Style Practical Method Taijiquan, which has turned it into a science. I have only scratched the surface in terms of understanding, but it still has increased my martial ability considerably.