There is a famous saying:
The upper class Feng Shui masters watch the stars, [上等地师看星斗]
The middle class Feng Shui masters watch the water mouths, [中等地师看水口]
The lower class Feng Shui masters roam in the mountains. [下等地师随山走]
The term 地师 can be translated as "Earth Master" meaning a person whose profession involves analyzing Earth qi. A person whose profession involves communicating with Heaven is known as 天师 (For example, the daoist grandmaster Zhang Dao Ling 张道陵 is better known as 张天师). A person whose profession is teaching is known as 人师 (For example, to take up the teaching professional is called 为人师表). Obviously, an Earth Master is better known as a Feng Shui Master.
Most people misunderstand the saying as classifying Feng Shui masters into 3 categories. In fact, it tells the three stages of training of Feng Shui masters.
The lower class refers to the beginners. They have to follow the master to feel the earth qi by walking the dragon. I went through this stage without knowing when I was a child playing in the mountains without shoes. In those days, wearing shoes is a luxury.
The middle class refers to apprentices following the master learning how to measure water mouths using the luopan. This includes measuring the incoming mountain dragon and the facing to erect a monument stone. This part is mainly studying the landforms.
The upper class refers to the third stage when the disciples learn the Li Qi part of Feng Shui. The stars refer to the nine stars different schools use in their Feng Shui practices.
Only when the three stages have been completed one can be called a Feng Shui master.
If you miss first stage, please start visiting the mountains.