In the long fist system, before I train any form, I do all the stretching, kicking drills, and punching drills.
One of the punching drills (usually 60 rep) that I do is:
1. Face north.
2. Stand both feet with shoulder width with fists on both sides of the waist.
3. Drop down to low horse stance.
4. Straight both legs (power from ground and up), turn body to the west (power from back to front), and punch out right fist. The right arm, right shoulder, chest, and back shoulder are all in one perfect straight line (this give the maximum reach).
5. Repeat 3, 4 for the other side.