It's a good idea to free up the Pelvis and Sacral area.
This is important so you can connect to the legs and access the intrinsic, elastic energy that is present. The pelvis free floats like a Buoy in water.
Any pressure on the arms, like in ward off for example, is instantly taken down to the legs and feet through the pelvis and then discharged.
There are lots of books with good exercise. I'm currently working my way through "Meet your Body" by Noah Karrasch, published by Singing Dragon Press. Feldenkreis is also an interesting investigation.
Research and see how your Practise is informed.