Chinese Kung-fu is usually divided into two schools: North School and the South. However, the essences and theories of both schools are nearly the same. The only difference lies on the forms of Kung-fu in practicing or in people's understanding as a result of region and culture variety through the country.
The most distinguish feature between North School Kung-fu and the South is in the application of fighting techniques. In the North, people usually attack others by their kicking. It is ever clearly described in a saying "in any actual fighting, a fighter of the North will certainly use his hands only to protect his body like a gate. It is his kicking attacking his opponent completely." While in the South, a fighter is not so good in using his feet, instead, he would use the Yao (waist), Ma (stance), Qiao Shou(hand movements) to attack another in a short distance with instant and fierce force. This fighting technique emphasizes the application of Jin (tendon), Gu (skeleton), Qi (breathing), and the coordination of one's internal strength and his outside movements. You could defend yourself and attack another just in one movement. I was very keen on practicing South School Kung-fu when I was young and, has ever learnt Hong Quan, Pak Mei Quan and wing Chun Quan. Those Quan are the same in their essences but different in styles. They all possess the distinguish feature of South School Kung-fu: attacking other by Yao, Ma and Qiaoshou rather than by their feet in kicking.
Yao, Ma and Qiao Shao are the most distinguish features as well as the most basic concepts in South School Kung-fu. In actual fighting, they will assist each other. They are connected with each other in a close way. In my own understanding with my experience in practicing Kung-fu for so many years, to master the basic technique of Yao, Ma and Qiao Shou is the only way to learn South School Kung-fu well. To practice Gong Fa is a vital point to learn Yao, Maad Qiao Shou well. To begin with, you should have a good understanding of the physiological construction of human body, as well as practicing Jin, Gu, Qi and Liu Jin (six forces). Liu Jin means the most basical original strength in the human body might be led to six different directions. Human beings develop the strength to six directions-upward, downward, leftward, rightward, forward and backward-in a natural way in the process of laboring or fighting. In actual practicing, you would know that when you are sending your force out to one direction, your body would unconsciously produce one kind of force to the opposite direction so as to keep your body in balance. You could get this experience when you are moving a heavy box forward or lifting a big bag upward in your daily life. This opposite force is the instinct and basic rule of human body. As a saying goes: "when you apply your force upward, outward and forward, there would be an opposite one accordingly downward, inward or backward." The great forefathers of Kung-fu had made full use of this rule of human body and developed it as a kind of forces and strength in Kung-fu through effective practicing ways for thousands of years of its development. When you are applying this forces in an actual fighting, you could better define yourself and attach others.
Unfortunately, most of the essential practicing methods and theories created and issued by the grand masters have been lost today. However, we could still find out its trace in many sets of routines in traditional South School Kung-fu. It is especially seen in the sets of routine of Hong Zha Ma Tui Zhang (push the palms in horse-riding stance), your hands will be moved forward, backward, leftward, rightward, upward and downward driving your Jin, Gu, Qi inside your body to move accordingly. Some routines in Pak Mci Quan, such as Zhi Bu Quan (straight fist), Shi Zi Quan (crossed fist), Liu Jing Jiu Bu Tui Quan (pushing fist with six strength in nine stance), also reflect the uses of this rule of human body. Through effective training methods in extending muscles and bones with the application of your Liu Jing, you could enhance the functions of your joins and improve their moving ability. In the training process, you could keep your Qi in your abdomen, and drive your Jin, Gu, Qi moving inside your body so as to make Liu Jin move freely to any or all directions at your will. Thus, the six forces would be sent out in a rolling way getting much more powerful.
Actually, your mind and understanding in practicing Kung-fu is certainly shown markedly in many South School Kung-fu, such as "Tie Xian Quan", "San Gong Fu Hu Quan "and "Shuang Gong Fu Hu Quan" in Hong Quan, "Zhi Bu Quan", "Shi Zi Quan", "San Men Ba Gua Quan", "Liu Bu Qiu Jing Tui Quan" and "Shi Ba Mo Qiao" in Pak Mci Quan. In my understanding, both of these two Quan apply my forces from a straight route to a round one, so as to improve my ability to move upward and downward, inward and outward, forward and backward. Thus I could really reach the level in sending out my forces in a round rolling way.
How to practice Liu JIn in Yao, Ma and Qiao Shao? In my opinion, you should understand two forces well. You'd better practice the forces separately from six different directions: upward, downward leftward, rightward, forward and backward. Only in this way could you practice it well. You could practice the techniques of Yao, Ma and Qiao Shao together or even separately. The point is that you should have a clear purpose to practice and make sure that you have practiced it to the point, thus you could reach the goal in improving your Kung-fu as well.