There are many secrets but most commonly people forget to do things like watch their body language. You should look your acquaintance in the eyes, shake their hand firmly, watch your body language to not seem insecure or anything like that, and you can make a great first impression like this.
The expedition to Bartolomeu Dias in 1487-1488 years rounded the southern extremity of Africa and in 1488 opened a cape, named Cape of Good Hope. In 1487, at the head of the expedition, which was aimed to find the sea route to India, explored south-west coast of Africa from 22 ° to 33 ° south latitude. The first of the Europeans skirted Africa from the south side. Passing along the southern coast of Africa to the Bay of Algoa was forced to turn to Portugal on demand of the team; On the way back opened the Cape of Good Hope (1488).
The answer is: Pre operational stages.
According to piaget's theory, children will started to recognize and learn to manipulate symbols during pre operational stages.
They will start to understand hand gestures, facial expression, and voice intonation that given by other people.
To put it on a simple term, psychology is the study to know why our mind works.
Behavior is not the only thing covered by psychology. It's a huge factor of it, but not all of it.
Psychology also teach us on why people developed a certain opinion, how people developed a certain preference, how interaction with other people affect our minds, etc.